diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.Indexer.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.Indexer.cs
index 89d71d72..75805cb1 100644
--- a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.Indexer.cs
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.Indexer.cs
@@ -8,9 +8,15 @@ namespace PrimeFuncPack.Core.Tests;
 partial class FlatArrayBuilderTest
 {
     [Theory]
+    [InlineData(int.MinValue)]
+    [InlineData(int.MinValue + 1)]
+    [InlineData(MinusFifteen)]
     [InlineData(-1)]
     [InlineData(0)]
     [InlineData(1)]
+    [InlineData(PlusFifteen)]
+    [InlineData(int.MaxValue - 1)]
+    [InlineData(int.MaxValue)]
     public void Indexer_SourceIsDefault_ExpectIndexOutOfRangeException(int index)
     {
         var source = new FlatArray<StructType>.Builder();
@@ -19,10 +25,16 @@ public void Indexer_SourceIsDefault_ExpectIndexOutOfRangeException(int index)
     }
 
     [Theory]
-    [InlineData(0, 1, TabString)]
+    [InlineData(0, 1, EmptyString)]
+    [InlineData(0, 2, AnotherString, SomeString, LowerSomeString)]
     [InlineData(1, 2, AnotherString, SomeString, LowerSomeString)]
-    [InlineData(2, 3, AnotherString, AnotherString, null, SomeString)]
-    [InlineData(3, 4, "Zero", "One", "Two", "Three")]
+    [InlineData(0, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(1, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(2, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(0, 4, null, "One", "Two", "Three")]
+    [InlineData(1, 4, null, "One", "Two", "Three")]
+    [InlineData(2, 4, null, "One", "Two", "Three")]
+    [InlineData(3, 4, null, "One", "Two", "Three")]
     public void Indexer_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
         int index, int sourceLength, params string?[] sourceItems)
     {
@@ -35,10 +47,42 @@ public void Indexer_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
     }
 
     [Theory]
+    // Effective Length: 1, Inner array length: 1
+    [InlineData(int.MinValue, 1, SomeString)]
+    [InlineData(int.MinValue + 1, 1, SomeString)]
+    [InlineData(MinusFifteen, 1, SomeString)]
+    [InlineData(-1, 1, SomeString)]
     [InlineData(1, 1, SomeString)]
-    [InlineData(1, 1, AnotherString, SomeString)]
-    [InlineData(5, 2, EmptyString, TabString)]
+    [InlineData(PlusFifteen, 1, SomeString)]
+    [InlineData(int.MaxValue - 1, 1, SomeString)]
+    [InlineData(int.MaxValue, 1, SomeString)]
+    // Effective Length: 1, Inner array length: 2
+    [InlineData(int.MinValue, 1, EmptyString, AnotherString)]
+    [InlineData(int.MinValue + 1, 1, EmptyString, AnotherString)]
+    [InlineData(MinusFifteen, 1, EmptyString, AnotherString)]
+    [InlineData(-1, 1, EmptyString, AnotherString)]
+    [InlineData(1, 1, EmptyString, AnotherString)]
+    [InlineData(PlusFifteen, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue - 1, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue, 1, EmptyString, AnotherString)]
+    // Effective Length: 2, Inner array length: 2
+    [InlineData(int.MinValue, 2, EmptyString, SomeString)]
+    [InlineData(int.MinValue + 1, 2, EmptyString, SomeString)]
+    [InlineData(MinusFifteen, 2, EmptyString, SomeString)]
+    [InlineData(-1, 2, EmptyString, SomeString)]
+    [InlineData(2, 2, EmptyString, SomeString)]
+    [InlineData(PlusFifteen, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue - 1, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue, 2, EmptyString, SomeString)]
+    // Effective Length: 3, Inner array length: 3
+    [InlineData(int.MinValue, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MinValue + 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(MinusFifteen, 3, LowerSomeString, null, SomeString)]
     [InlineData(-1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(3, 3, LowerSomeString, null, SomeString)]
+    [InlineData(PlusFifteen, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue - 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue, 3, LowerSomeString, null, SomeString)]
     public void Indexer_IndexIsOutOfRange_ExpectIndexOutOfRangeException(
         int index, int sourceLength, params string?[] sourceItems)
     {
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.IndexerRef.IndexFromEnd.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.IndexerRef.IndexFromEnd.cs
new file mode 100644
index 00000000..04aca244
--- /dev/null
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.IndexerRef.IndexFromEnd.cs
@@ -0,0 +1,76 @@
+using System;
+using PrimeFuncPack.UnitTest;
+using Xunit;
+using static PrimeFuncPack.UnitTest.TestData;
+
+namespace PrimeFuncPack.Core.Tests;
+
+partial class FlatArrayBuilderTest
+{
+    [Theory]
+    [InlineData(0)]
+    [InlineData(1)]
+    [InlineData(PlusFifteen)]
+    [InlineData(int.MaxValue - 1)]
+    [InlineData(int.MaxValue)]
+    public void IndexerRef_IndexFromEnd_SourceIsDefault_ExpectIndexOutOfRangeException(int indexFromEnd)
+    {
+        var fromEnd = Index.FromEnd(indexFromEnd);
+
+        var source = new FlatArray<StructType>.Builder();
+
+        _ = Assert.Throws<IndexOutOfRangeException>(() => _ = source.ItemRef(fromEnd));
+    }
+
+    [Theory]
+    [InlineData(0, 1, 1, EmptyString)]
+    [InlineData(0, 2, 2, AnotherString, SomeString, LowerSomeString)]
+    [InlineData(0, 3, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(0, 4, 4, null, "One", "Two", "Three")]
+    [InlineData(1, 1, 2, AnotherString, SomeString, LowerSomeString)]
+    [InlineData(2, 1, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(3, 1, 4, null, "One", "Two", "Three")]
+    public void IndexerRef_IndexFromEnd_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
+        int index, int indexFromEnd, int sourceLength, params string?[] sourceItems)
+    {
+        var fromEnd = Index.FromEnd(indexFromEnd);
+
+        var source = sourceItems.InitializeFlatArrayBuilder(sourceLength);
+
+        var actual = source.ItemRef(fromEnd);
+        var expected = sourceItems[index];
+
+        Assert.Equal(expected, actual);
+    }
+
+    [Theory]
+    // Effective Length: 1, Inner array length: 1
+    [InlineData(0, 1, SomeString)]
+    [InlineData(2, 1, SomeString)]
+    [InlineData(int.MaxValue - 1, 1, SomeString)]
+    [InlineData(int.MaxValue, 1, SomeString)]
+    // Effective Length: 1, Inner array length: 2
+    [InlineData(0, 1, EmptyString, AnotherString)]
+    [InlineData(2, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue - 1, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue, 1, EmptyString, AnotherString)]
+    // Effective Length: 2, Inner array length: 2
+    [InlineData(0, 2, EmptyString, SomeString)]
+    [InlineData(3, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue - 1, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue, 2, EmptyString, SomeString)]
+    // Effective Length: 3, Inner array length: 3
+    [InlineData(0, 3, LowerSomeString, null, SomeString)]
+    [InlineData(4, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue - 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue, 3, LowerSomeString, null, SomeString)]
+    public void IndexerRef_IndexFromEnd_IndexIsOutOfRange_ExpectIndexOutOfRangeException(
+        int indexFromEnd, int sourceLength, params string?[] sourceItems)
+    {
+        var fromEnd = Index.FromEnd(indexFromEnd);
+
+        var source = sourceItems.InitializeFlatArrayBuilder(sourceLength);
+
+        _ = Assert.Throws<IndexOutOfRangeException>(() => _ = source.ItemRef(fromEnd));
+    }
+}
\ No newline at end of file
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.IndexerRef.IndexFromStart.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.IndexerRef.IndexFromStart.cs
new file mode 100644
index 00000000..ace1253c
--- /dev/null
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.IndexerRef.IndexFromStart.cs
@@ -0,0 +1,79 @@
+using System;
+using PrimeFuncPack.UnitTest;
+using Xunit;
+using static PrimeFuncPack.UnitTest.TestData;
+
+namespace PrimeFuncPack.Core.Tests;
+
+partial class FlatArrayBuilderTest
+{
+    [Theory]
+    [InlineData(0)]
+    [InlineData(1)]
+    [InlineData(PlusFifteen)]
+    [InlineData(int.MaxValue - 1)]
+    [InlineData(int.MaxValue)]
+    public void IndexerRef_IndexFromStart_SourceIsDefault_ExpectIndexOutOfRangeException(int index)
+    {
+        var fromStart = Index.FromStart(index);
+
+        var source = new FlatArray<StructType>.Builder();
+
+        _ = Assert.Throws<IndexOutOfRangeException>(() => _ = source.ItemRef(fromStart));
+    }
+
+    [Theory]
+    [InlineData(0, 1, EmptyString)]
+    [InlineData(0, 2, AnotherString, SomeString, LowerSomeString)]
+    [InlineData(1, 2, AnotherString, SomeString, LowerSomeString)]
+    [InlineData(0, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(1, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(2, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(0, 4, null, "One", "Two", "Three")]
+    [InlineData(1, 4, null, "One", "Two", "Three")]
+    [InlineData(2, 4, null, "One", "Two", "Three")]
+    [InlineData(3, 4, null, "One", "Two", "Three")]
+    public void IndexerRef_IndexFromStart_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
+        int index, int sourceLength, params string?[] sourceItems)
+    {
+        var fromStart = Index.FromStart(index);
+
+        var source = sourceItems.InitializeFlatArrayBuilder(sourceLength);
+
+        var actual = source.ItemRef(fromStart);
+        var expected = sourceItems[index];
+
+        Assert.Equal(expected, actual);
+    }
+
+    [Theory]
+    // Effective Length: 1, Inner array length: 1
+    [InlineData(1, 1, SomeString)]
+    [InlineData(PlusFifteen, 1, SomeString)]
+    [InlineData(int.MaxValue - 1, 1, SomeString)]
+    [InlineData(int.MaxValue, 1, SomeString)]
+    // Effective Length: 1, Inner array length: 2
+    [InlineData(1, 1, EmptyString, AnotherString)]
+    [InlineData(PlusFifteen, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue - 1, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue, 1, EmptyString, AnotherString)]
+    // Effective Length: 2, Inner array length: 2
+    [InlineData(2, 2, EmptyString, SomeString)]
+    [InlineData(PlusFifteen, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue - 1, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue, 2, EmptyString, SomeString)]
+    // Effective Length: 3, Inner array length: 3
+    [InlineData(3, 3, LowerSomeString, null, SomeString)]
+    [InlineData(PlusFifteen, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue - 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue, 3, LowerSomeString, null, SomeString)]
+    public void IndexerRef_IndexFromStart_IndexIsOutOfRange_ExpectIndexOutOfRangeException(
+        int index, int sourceLength, params string?[] sourceItems)
+    {
+        var fromStart = Index.FromStart(index);
+
+        var source = sourceItems.InitializeFlatArrayBuilder(sourceLength);
+
+        _ = Assert.Throws<IndexOutOfRangeException>(() => _ = source.ItemRef(fromStart));
+    }
+}
\ No newline at end of file
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.IndexerRef.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.IndexerRef.cs
index af0e51f7..b433a7df 100644
--- a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.IndexerRef.cs
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Builder/Builder.IndexerRef.cs
@@ -8,9 +8,15 @@ namespace PrimeFuncPack.Core.Tests;
 partial class FlatArrayBuilderTest
 {
     [Theory]
+    [InlineData(int.MinValue)]
+    [InlineData(int.MinValue + 1)]
+    [InlineData(MinusFifteen)]
     [InlineData(-1)]
     [InlineData(0)]
     [InlineData(1)]
+    [InlineData(PlusFifteen)]
+    [InlineData(int.MaxValue - 1)]
+    [InlineData(int.MaxValue)]
     public void IndexerRef_SourceIsDefault_ExpectIndexOutOfRangeException(int index)
     {
         var source = new FlatArray<StructType>.Builder();
@@ -19,10 +25,16 @@ public void IndexerRef_SourceIsDefault_ExpectIndexOutOfRangeException(int index)
     }
 
     [Theory]
-    [InlineData(0, 1, TabString)]
+    [InlineData(0, 1, EmptyString)]
+    [InlineData(0, 2, AnotherString, SomeString, LowerSomeString)]
     [InlineData(1, 2, AnotherString, SomeString, LowerSomeString)]
-    [InlineData(2, 3, AnotherString, AnotherString, null, SomeString)]
-    [InlineData(3, 4, "Zero", "One", "Two", "Three")]
+    [InlineData(0, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(1, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(2, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(0, 4, null, "One", "Two", "Three")]
+    [InlineData(1, 4, null, "One", "Two", "Three")]
+    [InlineData(2, 4, null, "One", "Two", "Three")]
+    [InlineData(3, 4, null, "One", "Two", "Three")]
     public void IndexerRef_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
         int index, int sourceLength, params string?[] sourceItems)
     {
@@ -35,10 +47,42 @@ public void IndexerRef_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
     }
 
     [Theory]
+    // Effective Length: 1, Inner array length: 1
+    [InlineData(int.MinValue, 1, SomeString)]
+    [InlineData(int.MinValue + 1, 1, SomeString)]
+    [InlineData(MinusFifteen, 1, SomeString)]
+    [InlineData(-1, 1, SomeString)]
     [InlineData(1, 1, SomeString)]
-    [InlineData(1, 1, AnotherString, SomeString)]
-    [InlineData(5, 2, EmptyString, TabString)]
+    [InlineData(PlusFifteen, 1, SomeString)]
+    [InlineData(int.MaxValue - 1, 1, SomeString)]
+    [InlineData(int.MaxValue, 1, SomeString)]
+    // Effective Length: 1, Inner array length: 2
+    [InlineData(int.MinValue, 1, EmptyString, AnotherString)]
+    [InlineData(int.MinValue + 1, 1, EmptyString, AnotherString)]
+    [InlineData(MinusFifteen, 1, EmptyString, AnotherString)]
+    [InlineData(-1, 1, EmptyString, AnotherString)]
+    [InlineData(1, 1, EmptyString, AnotherString)]
+    [InlineData(PlusFifteen, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue - 1, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue, 1, EmptyString, AnotherString)]
+    // Effective Length: 2, Inner array length: 2
+    [InlineData(int.MinValue, 2, EmptyString, SomeString)]
+    [InlineData(int.MinValue + 1, 2, EmptyString, SomeString)]
+    [InlineData(MinusFifteen, 2, EmptyString, SomeString)]
+    [InlineData(-1, 2, EmptyString, SomeString)]
+    [InlineData(2, 2, EmptyString, SomeString)]
+    [InlineData(PlusFifteen, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue - 1, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue, 2, EmptyString, SomeString)]
+    // Effective Length: 3, Inner array length: 3
+    [InlineData(int.MinValue, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MinValue + 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(MinusFifteen, 3, LowerSomeString, null, SomeString)]
     [InlineData(-1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(3, 3, LowerSomeString, null, SomeString)]
+    [InlineData(PlusFifteen, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue - 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue, 3, LowerSomeString, null, SomeString)]
     public void IndexerRef_IndexIsOutOfRange_ExpectIndexOutOfRangeException(
         int index, int sourceLength, params string?[] sourceItems)
     {
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.CollectionExpression.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.CollectionExpression.cs
new file mode 100644
index 00000000..49cddd08
--- /dev/null
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.CollectionExpression.cs
@@ -0,0 +1,26 @@
+#if NET8_0_OR_GREATER
+using System;
+using Xunit;
+using static PrimeFuncPack.UnitTest.TestData;
+
+namespace PrimeFuncPack.Core.Tests;
+
+partial class FlatArrayBuilderTest
+{
+    [Fact]
+    public static void ConstructFromCollectionExpression_SourceIsEmpty_ExpectDefault()
+    {
+        FlatArray<string?>.Builder actual = [];
+        actual.VerifyInnerState([], default);
+    }
+
+    [Fact]
+    public static void ConstructFromCollectionExpression_SourceIsNotEmpty_ExpectInnerStateIsSourceCollection()
+    {
+        FlatArray<string?>.Builder actual = [ SomeString, null, EmptyString, WhiteSpaceString, AnotherString ];
+        string?[] expectedItems = [ SomeString, null, EmptyString, WhiteSpaceString, AnotherString ];
+
+        actual.VerifyInnerState(expectedItems, expectedItems.Length);
+    }
+}
+#endif
\ No newline at end of file
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.Array.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.Array.cs
new file mode 100644
index 00000000..367a646f
--- /dev/null
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.Array.cs
@@ -0,0 +1,52 @@
+using System;
+using PrimeFuncPack.UnitTest;
+using Xunit;
+using static PrimeFuncPack.UnitTest.TestData;
+
+namespace PrimeFuncPack.Core.Tests;
+
+partial class FlatArrayBuilderTest
+{
+    [Fact]
+    public void FromArray_SourceIsNull_ExpectInnerStateIsDefault()
+    {
+        StructType[]? source = null;
+        var actual = FlatArray<StructType>.Builder.From(source);
+
+        actual.VerifyInnerState(Array.Empty<StructType>(), default);
+    }
+
+    [Fact]
+    public void FromArray_SourceIsEmpty_ExpectInnerStateIsDefault()
+    {
+        var source = Array.Empty<RecordType>();
+        var actual = FlatArray<RecordType>.Builder.From(source);
+
+        actual.VerifyInnerState(Array.Empty<RecordType>(), default);
+    }
+
+    [Theory]
+    [InlineData(Zero)]
+    [InlineData(PlusFifteen, Zero, MinusFifteen, PlusFifteen)]
+    [InlineData(12, 15, 1, 91, 7, -95, 975, 0, 5, 6, 7, 901, 98, -266, 78, 62, 21, 35, 75, 212, 51)]
+    public void FromArray_SourceIsNotEmpty_ExpectInnerStateIsSourceArray(
+        params int[] source)
+    {
+        var coppied = source.GetCopy();
+        var actual = FlatArray<int>.Builder.From(source);
+
+        actual.VerifyInnerState(coppied, coppied.Length);
+    }
+
+    [Fact]
+    public void FromArray_ThenModifySource_ExpectInnerStateHasNotChanged()
+    {
+        var sourceArray = new[] { "One", "Two", "Three" };
+        var actual = FlatArray<string>.Builder.From(sourceArray);
+
+        sourceArray[0] = "2";
+        var expectedItems = new[] { "One", "Two", "Three" };
+
+        actual.VerifyInnerState(expectedItems, expectedItems.Length);
+    }
+}
\ No newline at end of file
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.FlatArray.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.FlatArray.cs
new file mode 100644
index 00000000..2f5846ed
--- /dev/null
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.FlatArray.cs
@@ -0,0 +1,61 @@
+using System;
+using PrimeFuncPack.UnitTest;
+using Xunit;
+using static PrimeFuncPack.UnitTest.TestData;
+
+namespace PrimeFuncPack.Core.Tests;
+
+partial class FlatArrayBuilderTest
+{
+    [Fact]
+    public void FromFlatArray_SourceIsDefault_ExpectInnerStateIsDefault()
+    {
+        var source = default(FlatArray<RefType>);
+        var actual = FlatArray<RefType>.Builder.From(source);
+
+        actual.VerifyInnerState(Array.Empty<RefType>(), default);
+    }
+
+    [Theory]
+    [InlineData(SomeString, AnotherString)]
+    [InlineData(LowerSomeString, null, SomeString, EmptyString, WhiteSpaceString)]
+    public void FromFlatArray_SourceIsNotDefault_ExpectInnerStateIsSourceArray(
+        params string?[] sourceArray)
+    {
+        var coppied = sourceArray.GetCopy();
+
+        var source = sourceArray.InitializeFlatArray();
+        var actual = FlatArray<string?>.Builder.From(source);
+
+        actual.VerifyInnerState(coppied, coppied.Length);
+    }
+
+    [Fact]
+    public void FromNullableFlatArray_SourceIsNull_ExpectInnerStateIsDefault()
+    {
+        var source = default(FlatArray<StructType?>?);
+        var actual = FlatArray<StructType?>.Builder.From(source);
+
+        actual.VerifyInnerState(Array.Empty<StructType?>(), default);
+    }
+
+    [Fact]
+    public void FromNullableFlatArray_SourceIsDefault_ExpectInnerStateIsDefault()
+    {
+        FlatArray<RecordType>? source = default(FlatArray<RecordType>);
+        var actual = FlatArray<RecordType>.Builder.From(source);
+
+        actual.VerifyInnerState(Array.Empty<RecordType>(), default);
+    }
+
+    [Fact]
+    public void FromNullableFlatArray_SourceIsNotDefault_ExpectInnerStateIsSourceArray()
+    {
+        FlatArray<bool?>? source = new bool?[] { false, null, true }.InitializeFlatArray(2);
+
+        var actual = FlatArray<bool?>.Builder.From(source);
+        var expectedItems = new bool?[] { false, null };
+
+        actual.VerifyInnerState(expectedItems, expectedItems.Length);
+    }
+}
\ No newline at end of file
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.ImmutableArray.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.ImmutableArray.cs
new file mode 100644
index 00000000..d459664f
--- /dev/null
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.ImmutableArray.cs
@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Immutable;
+using PrimeFuncPack.UnitTest;
+using Xunit;
+using static PrimeFuncPack.UnitTest.TestData;
+
+namespace PrimeFuncPack.Core.Tests;
+
+partial class FlatArrayBuilderTest
+{
+    [Fact]
+    public void FromImmutableArray_SourceIsDefault_ExpectInnerStateIsDefault()
+    {
+        var source = default(ImmutableArray<long?>);
+        var actual = FlatArray<long?>.Builder.From(source);
+
+        actual.VerifyInnerState(Array.Empty<long?>(), default);
+    }
+
+    [Theory]
+    [InlineData(SomeString)]
+    [InlineData(LowerSomeString, null, AnotherString)]
+    public void FromImmutableArray_SourceIsNotDefault_ExpectInnerStateAreSourceItems(
+        params string?[] sourceArray)
+    {
+        var coppied = sourceArray.GetCopy();
+
+        var source = sourceArray.ToImmutableArray();
+        var actual = FlatArray<string?>.Builder.From(source);
+
+        actual.VerifyInnerState(coppied, coppied.Length);
+    }
+
+    [Fact]
+    public void FromNullableImmutableArray_SourceIsNull_ExpectInnerStateIsDefault()
+    {
+        ImmutableArray<RecordType>? source = null;
+        var actual = FlatArray<RecordType>.Builder.From(source);
+
+        actual.VerifyInnerState(Array.Empty<RecordType>(), default);
+    }
+
+    [Fact]
+    public void FromNullableImmutableArray_SourceIsDefault_ExpectInnerStateIsDefault()
+    {
+        ImmutableArray<RefType?>? source = new ImmutableArray<RefType?>();;
+        var actual = FlatArray<RefType?>.Builder.From(source);
+
+        actual.VerifyInnerState(Array.Empty<RefType?>(), default);
+    }
+
+    [Theory]
+    [InlineData(PlusFifteen)]
+    [InlineData(null, MinusFifteen, Zero)]
+    public void FromNullableImmutableArray_SourceIsNotDefault_ExpectInnerStateAreSourceItems(
+        params int?[] sourceItems)
+    {
+        var coppied = sourceItems.GetCopy();
+
+        var source = sourceItems.ToImmutableArray();
+        var actual = FlatArray<int?>.Builder.From(source);
+
+        actual.VerifyInnerState(coppied, coppied.Length);
+    }
+}
\ No newline at end of file
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.List.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.List.cs
new file mode 100644
index 00000000..fc3284b1
--- /dev/null
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.List.cs
@@ -0,0 +1,69 @@
+using System;
+using System.Collections.Generic;
+using PrimeFuncPack.UnitTest;
+using Xunit;
+using static PrimeFuncPack.UnitTest.TestData;
+
+namespace PrimeFuncPack.Core.Tests;
+
+partial class FlatArrayBuilderTest
+{
+    [Fact]
+    public void FromList_SourceIsNull_ExpectInnerStateIsDefault()
+    {
+        List<DateOnly>? source = null;
+        var actual = FlatArray<DateOnly>.Builder.From(source);
+
+        actual.VerifyInnerState(Array.Empty<DateOnly>(), default);
+    }
+
+    [Fact]
+    public void FromList_SourceIsEmpty_ExpectInnerStateIsDefault()
+    {
+        var source = new List<RefType>();
+        var actual = FlatArray<RefType>.Builder.From(source);
+
+        actual.VerifyInnerState(Array.Empty<RefType>(), default);
+    }
+
+    [Fact]
+    public void FromList_SourceIsNotEmpty_ExpectInnerStateAreSourceItems()
+    {
+        var source = new List<RecordStruct?>
+        {
+            SomeTextRecordStruct, null, AnotherTextRecordStruct
+        };
+
+        var actual = FlatArray<RecordStruct?>.Builder.From(source);
+
+        const int expectedLength = 3;
+        var expectedItems = new RecordStruct?[]
+        {
+            SomeTextRecordStruct, null, AnotherTextRecordStruct
+        };
+
+        actual.VerifyInnerState(expectedItems, expectedLength);
+    }
+
+    [Fact]
+    public void FromList_ThenModifySource_ExpectInnerStateHasNotChanged()
+    {
+        var sourceList = new List<RecordType>
+        {
+            MinusFifteenIdSomeStringNameRecord, ZeroIdNullNameRecord, PlusFifteenIdSomeStringNameRecord
+        };
+
+        var actual = FlatArray<RecordType>.Builder.From(sourceList);
+
+        sourceList[0] = PlusFifteenIdLowerSomeStringNameRecord;
+        sourceList.Add(MinusFifteenIdNullNameRecord);
+
+        const int expectedLength = 3;
+        var expectedItems = new[]
+        {
+            MinusFifteenIdSomeStringNameRecord, ZeroIdNullNameRecord, PlusFifteenIdSomeStringNameRecord
+        };
+
+        actual.VerifyInnerState(expectedItems, expectedLength);
+    }
+}
\ No newline at end of file
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.cs
deleted file mode 100644
index 61c15a7c..00000000
--- a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T.Builder/Factory/Factory.From.cs
+++ /dev/null
@@ -1,220 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Collections.Immutable;
-using PrimeFuncPack.UnitTest;
-using Xunit;
-using static PrimeFuncPack.UnitTest.TestData;
-
-namespace PrimeFuncPack.Core.Tests;
-
-partial class FlatArrayBuilderTest
-{
-    [Fact]
-    public void FromArray_SourceIsNull_ExpectInnerStateIsDefault()
-    {
-        StructType[]? source = null;
-        var actual = FlatArray<StructType>.Builder.From(source);
-
-        actual.VerifyInnerState(Array.Empty<StructType>(), default);
-    }
-
-    [Fact]
-    public void FromArray_SourceIsEmpty_ExpectInnerStateIsDefault()
-    {
-        var source = Array.Empty<RecordType>();
-        var actual = FlatArray<RecordType>.Builder.From(source);
-
-        actual.VerifyInnerState(Array.Empty<RecordType>(), default);
-    }
-
-    [Theory]
-    [InlineData(Zero)]
-    [InlineData(PlusFifteen, Zero, MinusFifteen, PlusFifteen)]
-    [InlineData(12, 15, 1, 91, 7, -95, 975, 0, 5, 6, 7, 901, 98, -266, 78, 62, 21, 35, 75, 212, 51)]
-    public void FromArray_SourceIsNotEmpty_ExpectInnerStateIsSourceArray(
-        params int[] source)
-    {
-        var coppied = source.GetCopy();
-        var actual = FlatArray<int>.Builder.From(source);
-
-        actual.VerifyInnerState(coppied, coppied.Length);
-    }
-
-    [Fact]
-    public void FromArray_ThenModifySource_ExpectInnerStateHasNotChanged()
-    {
-        var sourceArray = new[] { "One", "Two", "Three" };
-        var actual = FlatArray<string>.Builder.From(sourceArray);
-
-        sourceArray[0] = "2";
-        var expectedItems = new[] { "One", "Two", "Three" };
-
-        actual.VerifyInnerState(expectedItems, expectedItems.Length);
-    }
-
-    [Fact]
-    public void FromFlatArray_SourceIsDefault_ExpectInnerStateIsDefault()
-    {
-        var source = default(FlatArray<RefType>);
-        var actual = FlatArray<RefType>.Builder.From(source);
-
-        actual.VerifyInnerState(Array.Empty<RefType>(), default);
-    }
-
-    [Theory]
-    [InlineData(SomeString, AnotherString)]
-    [InlineData(LowerSomeString, null, SomeString, EmptyString, WhiteSpaceString)]
-    public void FromFlatArray_SourceIsNotDefault_ExpectInnerStateIsSourceArray(
-        params string?[] sourceArray)
-    {
-        var coppied = sourceArray.GetCopy();
-
-        var source = sourceArray.InitializeFlatArray();
-        var actual = FlatArray<string?>.Builder.From(source);
-
-        actual.VerifyInnerState(coppied, coppied.Length);
-    }
-
-    [Fact]
-    public void FromNullableFlatArray_SourceIsNull_ExpectInnerStateIsDefault()
-    {
-        var source = default(FlatArray<StructType?>?);
-        var actual = FlatArray<StructType?>.Builder.From(source);
-
-        actual.VerifyInnerState(Array.Empty<StructType?>(), default);
-    }
-
-    [Fact]
-    public void FromNullableFlatArray_SourceIsDefault_ExpectInnerStateIsDefault()
-    {
-        FlatArray<RecordType>? source = default(FlatArray<RecordType>);
-        var actual = FlatArray<RecordType>.Builder.From(source);
-
-        actual.VerifyInnerState(Array.Empty<RecordType>(), default);
-    }
-
-    [Fact]
-    public void FromNullableFlatArray_SourceIsNotDefault_ExpectInnerStateIsSourceArray()
-    {
-        FlatArray<bool?>? source = new bool?[] { false, null, true }.InitializeFlatArray(2);
-
-        var actual = FlatArray<bool?>.Builder.From(source);
-        var expectedItems = new bool?[] { false, null };
-
-        actual.VerifyInnerState(expectedItems, expectedItems.Length);
-    }
-
-    [Fact]
-    public void FromList_SourceIsNull_ExpectInnerStateIsDefault()
-    {
-        List<DateOnly>? source = null;
-        var actual = FlatArray<DateOnly>.Builder.From(source);
-
-        actual.VerifyInnerState(Array.Empty<DateOnly>(), default);
-    }
-
-    [Fact]
-    public void FromList_SourceIsEmpty_ExpectInnerStateIsDefault()
-    {
-        var source = new List<RefType>();
-        var actual = FlatArray<RefType>.Builder.From(source);
-
-        actual.VerifyInnerState(Array.Empty<RefType>(), default);
-    }
-
-    [Fact]
-    public void FromList_SourceIsNotEmpty_ExpectInnerStateAreSourceItems()
-    {
-        var source = new List<RecordStruct?>
-        {
-            SomeTextRecordStruct, null, AnotherTextRecordStruct
-        };
-
-        var actual = FlatArray<RecordStruct?>.Builder.From(source);
-
-        const int expectedLength = 3;
-        var expectedItems = new RecordStruct?[]
-        {
-            SomeTextRecordStruct, null, AnotherTextRecordStruct
-        };
-
-        actual.VerifyInnerState(expectedItems, expectedLength);
-    }
-
-    [Fact]
-    public void FromList_ThenModifySource_ExpectInnerStateHasNotChanged()
-    {
-        var sourceList = new List<RecordType>
-        {
-            MinusFifteenIdSomeStringNameRecord, ZeroIdNullNameRecord, PlusFifteenIdSomeStringNameRecord
-        };
-
-        var actual = FlatArray<RecordType>.Builder.From(sourceList);
-
-        sourceList[0] = PlusFifteenIdLowerSomeStringNameRecord;
-        sourceList.Add(MinusFifteenIdNullNameRecord);
-
-        const int expectedLength = 3;
-        var expectedItems = new[]
-        {
-            MinusFifteenIdSomeStringNameRecord, ZeroIdNullNameRecord, PlusFifteenIdSomeStringNameRecord
-        };
-
-        actual.VerifyInnerState(expectedItems, expectedLength);
-    }
-
-    [Fact]
-    public void FromImmutableArray_SourceIsDefault_ExpectInnerStateIsDefault()
-    {
-        var source = default(ImmutableArray<long?>);
-        var actual = FlatArray<long?>.Builder.From(source);
-
-        actual.VerifyInnerState(Array.Empty<long?>(), default);
-    }
-
-    [Theory]
-    [InlineData(SomeString)]
-    [InlineData(LowerSomeString, null, AnotherString)]
-    public void FromImmutableArray_SourceIsNotDefault_ExpectInnerStateAreSourceItems(
-        params string?[] sourceArray)
-    {
-        var coppied = sourceArray.GetCopy();
-
-        var source = sourceArray.ToImmutableArray();
-        var actual = FlatArray<string?>.Builder.From(source);
-
-        actual.VerifyInnerState(coppied, coppied.Length);
-    }
-
-    [Fact]
-    public void FromNullableImmutableArray_SourceIsNull_ExpectInnerStateIsDefault()
-    {
-        ImmutableArray<RecordType>? source = null;
-        var actual = FlatArray<RecordType>.Builder.From(source);
-
-        actual.VerifyInnerState(Array.Empty<RecordType>(), default);
-    }
-
-    [Fact]
-    public void FromNullableImmutableArray_SourceIsDefault_ExpectInnerStateIsDefault()
-    {
-        ImmutableArray<RefType?>? source = new ImmutableArray<RefType?>();;
-        var actual = FlatArray<RefType?>.Builder.From(source);
-
-        actual.VerifyInnerState(Array.Empty<RefType?>(), default);
-    }
-
-    [Theory]
-    [InlineData(PlusFifteen)]
-    [InlineData(null, MinusFifteen, Zero)]
-    public void FromNullableImmutableArray_SourceIsNotDefault_ExpectInnerStateAreSourceItems(
-        params int?[] sourceItems)
-    {
-        var coppied = sourceItems.GetCopy();
-
-        var source = sourceItems.ToImmutableArray();
-        var actual = FlatArray<int?>.Builder.From(source);
-
-        actual.VerifyInnerState(coppied, coppied.Length);
-    }
-}
\ No newline at end of file
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.Indexer.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.Indexer.cs
index a85a2523..576f9798 100644
--- a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.Indexer.cs
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.Indexer.cs
@@ -8,9 +8,15 @@ namespace PrimeFuncPack.Core.Tests;
 partial class FlatArrayTest
 {
     [Theory]
+    [InlineData(int.MinValue)]
+    [InlineData(int.MinValue + 1)]
     [InlineData(MinusFifteen)]
-    [InlineData(Zero)]
+    [InlineData(-1)]
+    [InlineData(0)]
+    [InlineData(1)]
     [InlineData(PlusFifteen)]
+    [InlineData(int.MaxValue - 1)]
+    [InlineData(int.MaxValue)]
     public void Indexer_SourceIsDefault_ExpectIndexOutOfRangeException(int index)
     {
         var source = default(FlatArray<RefType>);
@@ -23,8 +29,14 @@ void Test()
 
     [Theory]
     [InlineData(0, 1, EmptyString)]
+    [InlineData(0, 2, AnotherString, SomeString, LowerSomeString)]
     [InlineData(1, 2, AnotherString, SomeString, LowerSomeString)]
+    [InlineData(0, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(1, 3, SomeString, AnotherString, null, LowerSomeString)]
     [InlineData(2, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(0, 4, null, "One", "Two", "Three")]
+    [InlineData(1, 4, null, "One", "Two", "Three")]
+    [InlineData(2, 4, null, "One", "Two", "Three")]
     [InlineData(3, 4, null, "One", "Two", "Three")]
     public void Indexer_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
         int index, int sourceLength, params string?[] sourceItems)
@@ -38,10 +50,42 @@ public void Indexer_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
     }
 
     [Theory]
+    // Effective Length: 1, Inner array length: 1
+    [InlineData(int.MinValue, 1, SomeString)]
+    [InlineData(int.MinValue + 1, 1, SomeString)]
+    [InlineData(MinusFifteen, 1, SomeString)]
+    [InlineData(-1, 1, SomeString)]
     [InlineData(1, 1, SomeString)]
+    [InlineData(PlusFifteen, 1, SomeString)]
+    [InlineData(int.MaxValue - 1, 1, SomeString)]
+    [InlineData(int.MaxValue, 1, SomeString)]
+    // Effective Length: 1, Inner array length: 2
+    [InlineData(int.MinValue, 1, EmptyString, AnotherString)]
+    [InlineData(int.MinValue + 1, 1, EmptyString, AnotherString)]
+    [InlineData(MinusFifteen, 1, EmptyString, AnotherString)]
+    [InlineData(-1, 1, EmptyString, AnotherString)]
     [InlineData(1, 1, EmptyString, AnotherString)]
-    [InlineData(5, 2, EmptyString, SomeString)]
+    [InlineData(PlusFifteen, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue - 1, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue, 1, EmptyString, AnotherString)]
+    // Effective Length: 2, Inner array length: 2
+    [InlineData(int.MinValue, 2, EmptyString, SomeString)]
+    [InlineData(int.MinValue + 1, 2, EmptyString, SomeString)]
+    [InlineData(MinusFifteen, 2, EmptyString, SomeString)]
+    [InlineData(-1, 2, EmptyString, SomeString)]
+    [InlineData(2, 2, EmptyString, SomeString)]
+    [InlineData(PlusFifteen, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue - 1, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue, 2, EmptyString, SomeString)]
+    // Effective Length: 3, Inner array length: 3
+    [InlineData(int.MinValue, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MinValue + 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(MinusFifteen, 3, LowerSomeString, null, SomeString)]
     [InlineData(-1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(3, 3, LowerSomeString, null, SomeString)]
+    [InlineData(PlusFifteen, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue - 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue, 3, LowerSomeString, null, SomeString)]
     public void Indexer_IndexIsOutOfRange_ExpectIndexOutOfRangeException(
         int index, int sourceLength, params string?[] sourceItems)
     {
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.IndexerRef.IndexFromEnd.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.IndexerRef.IndexFromEnd.cs
new file mode 100644
index 00000000..5c77cf80
--- /dev/null
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.IndexerRef.IndexFromEnd.cs
@@ -0,0 +1,82 @@
+using System;
+using PrimeFuncPack.UnitTest;
+using Xunit;
+using static PrimeFuncPack.UnitTest.TestData;
+
+namespace PrimeFuncPack.Core.Tests;
+
+partial class FlatArrayTest
+{
+    [Theory]
+    [InlineData(0)]
+    [InlineData(1)]
+    [InlineData(PlusFifteen)]
+    [InlineData(int.MaxValue - 1)]
+    [InlineData(int.MaxValue)]
+    public void IndexerRef_IndexFromEnd_SourceIsDefault_ExpectIndexOutOfRangeException(int indexFromEnd)
+    {
+        var fromEnd = Index.FromEnd(indexFromEnd);
+
+        var source = default(FlatArray<RefType>);
+        var ex = Assert.Throws<IndexOutOfRangeException>(Test);
+
+        void Test()
+            =>
+            _ = source.ItemRef(fromEnd);
+    }
+
+    [Theory]
+    [InlineData(0, 1, 1, EmptyString)]
+    [InlineData(0, 2, 2, AnotherString, SomeString, LowerSomeString)]
+    [InlineData(0, 3, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(0, 4, 4, null, "One", "Two", "Three")]
+    [InlineData(1, 1, 2, AnotherString, SomeString, LowerSomeString)]
+    [InlineData(2, 1, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(3, 1, 4, null, "One", "Two", "Three")]
+    public void IndexerRef_IndexFromEnd_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
+        int index, int indexFromEnd, int sourceLength, params string?[] sourceItems)
+    {
+        var fromEnd = Index.FromEnd(indexFromEnd);
+
+        var source = sourceItems.InitializeFlatArray(sourceLength);
+
+        var actual = source.ItemRef(fromEnd);
+        var expected = sourceItems[index];
+
+        Assert.Equal(expected, actual);
+    }
+
+    [Theory]
+    // Effective Length: 1, Inner array length: 1
+    [InlineData(0, 1, SomeString)]
+    [InlineData(2, 1, SomeString)]
+    [InlineData(int.MaxValue - 1, 1, SomeString)]
+    [InlineData(int.MaxValue, 1, SomeString)]
+    // Effective Length: 1, Inner array length: 2
+    [InlineData(0, 1, EmptyString, AnotherString)]
+    [InlineData(2, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue - 1, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue, 1, EmptyString, AnotherString)]
+    // Effective Length: 2, Inner array length: 2
+    [InlineData(0, 2, EmptyString, SomeString)]
+    [InlineData(3, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue - 1, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue, 2, EmptyString, SomeString)]
+    // Effective Length: 3, Inner array length: 3
+    [InlineData(0, 3, LowerSomeString, null, SomeString)]
+    [InlineData(4, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue - 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue, 3, LowerSomeString, null, SomeString)]
+    public void IndexerRef_IndexFromEnd_IndexIsOutOfRange_ExpectIndexOutOfRangeException(
+        int indexFromEnd, int sourceLength, params string?[] sourceItems)
+    {
+        var fromEnd = Index.FromEnd(indexFromEnd);
+
+        var source = sourceItems.InitializeFlatArray(sourceLength);
+        var ex = Assert.Throws<IndexOutOfRangeException>(Test);
+
+        void Test()
+            =>
+            _ = source.ItemRef(fromEnd);
+    }
+}
\ No newline at end of file
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.IndexerRef.IndexFromStart.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.IndexerRef.IndexFromStart.cs
new file mode 100644
index 00000000..fcc1ab7f
--- /dev/null
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.IndexerRef.IndexFromStart.cs
@@ -0,0 +1,85 @@
+using System;
+using PrimeFuncPack.UnitTest;
+using Xunit;
+using static PrimeFuncPack.UnitTest.TestData;
+
+namespace PrimeFuncPack.Core.Tests;
+
+partial class FlatArrayTest
+{
+    [Theory]
+    [InlineData(0)]
+    [InlineData(1)]
+    [InlineData(PlusFifteen)]
+    [InlineData(int.MaxValue - 1)]
+    [InlineData(int.MaxValue)]
+    public void IndexerRef_IndexFromStart_SourceIsDefault_ExpectIndexOutOfRangeException(int index)
+    {
+        var fromStart = Index.FromStart(index);
+
+        var source = default(FlatArray<RefType>);
+        var ex = Assert.Throws<IndexOutOfRangeException>(Test);
+
+        void Test()
+            =>
+            _ = source.ItemRef(fromStart);
+    }
+
+    [Theory]
+    [InlineData(0, 1, EmptyString)]
+    [InlineData(0, 2, AnotherString, SomeString, LowerSomeString)]
+    [InlineData(1, 2, AnotherString, SomeString, LowerSomeString)]
+    [InlineData(0, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(1, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(2, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(0, 4, null, "One", "Two", "Three")]
+    [InlineData(1, 4, null, "One", "Two", "Three")]
+    [InlineData(2, 4, null, "One", "Two", "Three")]
+    [InlineData(3, 4, null, "One", "Two", "Three")]
+    public void IndexerRef_IndexFromStart_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
+        int index, int sourceLength, params string?[] sourceItems)
+    {
+        var fromStart = Index.FromStart(index);
+
+        var source = sourceItems.InitializeFlatArray(sourceLength);
+
+        var actual = source.ItemRef(fromStart);
+        var expected = sourceItems[index];
+
+        Assert.Equal(expected, actual);
+    }
+
+    [Theory]
+    // Effective Length: 1, Inner array length: 1
+    [InlineData(1, 1, SomeString)]
+    [InlineData(PlusFifteen, 1, SomeString)]
+    [InlineData(int.MaxValue - 1, 1, SomeString)]
+    [InlineData(int.MaxValue, 1, SomeString)]
+    // Effective Length: 1, Inner array length: 2
+    [InlineData(1, 1, EmptyString, AnotherString)]
+    [InlineData(PlusFifteen, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue - 1, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue, 1, EmptyString, AnotherString)]
+    // Effective Length: 2, Inner array length: 2
+    [InlineData(2, 2, EmptyString, SomeString)]
+    [InlineData(PlusFifteen, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue - 1, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue, 2, EmptyString, SomeString)]
+    // Effective Length: 3, Inner array length: 3
+    [InlineData(3, 3, LowerSomeString, null, SomeString)]
+    [InlineData(PlusFifteen, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue - 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue, 3, LowerSomeString, null, SomeString)]
+    public void IndexerRef_IndexFromStart_IndexIsOutOfRange_ExpectIndexOutOfRangeException(
+        int index, int sourceLength, params string?[] sourceItems)
+    {
+        var fromStart = Index.FromStart(index);
+
+        var source = sourceItems.InitializeFlatArray(sourceLength);
+        var ex = Assert.Throws<IndexOutOfRangeException>(Test);
+
+        void Test()
+            =>
+            _ = source.ItemRef(fromStart);
+    }
+}
\ No newline at end of file
diff --git a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.IndexerRef.cs b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.IndexerRef.cs
index 90141ca1..277b3a99 100644
--- a/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.IndexerRef.cs
+++ b/src/flatcollections-array/FlatArray.Tests/Tests.FlatArray.T/Array/Array.IndexerRef.cs
@@ -8,9 +8,15 @@ namespace PrimeFuncPack.Core.Tests;
 partial class FlatArrayTest
 {
     [Theory]
+    [InlineData(int.MinValue)]
+    [InlineData(int.MinValue + 1)]
     [InlineData(MinusFifteen)]
-    [InlineData(Zero)]
+    [InlineData(-1)]
+    [InlineData(0)]
+    [InlineData(1)]
     [InlineData(PlusFifteen)]
+    [InlineData(int.MaxValue - 1)]
+    [InlineData(int.MaxValue)]
     public void IndexerRef_SourceIsDefault_ExpectIndexOutOfRangeException(int index)
     {
         var source = default(FlatArray<RefType>);
@@ -23,8 +29,14 @@ void Test()
 
     [Theory]
     [InlineData(0, 1, EmptyString)]
+    [InlineData(0, 2, AnotherString, SomeString, LowerSomeString)]
     [InlineData(1, 2, AnotherString, SomeString, LowerSomeString)]
+    [InlineData(0, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(1, 3, SomeString, AnotherString, null, LowerSomeString)]
     [InlineData(2, 3, SomeString, AnotherString, null, LowerSomeString)]
+    [InlineData(0, 4, null, "One", "Two", "Three")]
+    [InlineData(1, 4, null, "One", "Two", "Three")]
+    [InlineData(2, 4, null, "One", "Two", "Three")]
     [InlineData(3, 4, null, "One", "Two", "Three")]
     public void IndexerRef_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
         int index, int sourceLength, params string?[] sourceItems)
@@ -38,10 +50,42 @@ public void IndexerRef_IndexIsInRange_ExpectItemIsFromSourceItemsByIndex(
     }
 
     [Theory]
+    // Effective Length: 1, Inner array length: 1
+    [InlineData(int.MinValue, 1, SomeString)]
+    [InlineData(int.MinValue + 1, 1, SomeString)]
+    [InlineData(MinusFifteen, 1, SomeString)]
+    [InlineData(-1, 1, SomeString)]
     [InlineData(1, 1, SomeString)]
+    [InlineData(PlusFifteen, 1, SomeString)]
+    [InlineData(int.MaxValue - 1, 1, SomeString)]
+    [InlineData(int.MaxValue, 1, SomeString)]
+    // Effective Length: 1, Inner array length: 2
+    [InlineData(int.MinValue, 1, EmptyString, AnotherString)]
+    [InlineData(int.MinValue + 1, 1, EmptyString, AnotherString)]
+    [InlineData(MinusFifteen, 1, EmptyString, AnotherString)]
+    [InlineData(-1, 1, EmptyString, AnotherString)]
     [InlineData(1, 1, EmptyString, AnotherString)]
-    [InlineData(5, 2, EmptyString, SomeString)]
+    [InlineData(PlusFifteen, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue - 1, 1, EmptyString, AnotherString)]
+    [InlineData(int.MaxValue, 1, EmptyString, AnotherString)]
+    // Effective Length: 2, Inner array length: 2
+    [InlineData(int.MinValue, 2, EmptyString, SomeString)]
+    [InlineData(int.MinValue + 1, 2, EmptyString, SomeString)]
+    [InlineData(MinusFifteen, 2, EmptyString, SomeString)]
+    [InlineData(-1, 2, EmptyString, SomeString)]
+    [InlineData(2, 2, EmptyString, SomeString)]
+    [InlineData(PlusFifteen, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue - 1, 2, EmptyString, SomeString)]
+    [InlineData(int.MaxValue, 2, EmptyString, SomeString)]
+    // Effective Length: 3, Inner array length: 3
+    [InlineData(int.MinValue, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MinValue + 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(MinusFifteen, 3, LowerSomeString, null, SomeString)]
     [InlineData(-1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(3, 3, LowerSomeString, null, SomeString)]
+    [InlineData(PlusFifteen, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue - 1, 3, LowerSomeString, null, SomeString)]
+    [InlineData(int.MaxValue, 3, LowerSomeString, null, SomeString)]
     public void IndexerRef_IndexIsOutOfRange_ExpectIndexOutOfRangeException(
         int index, int sourceLength, params string?[] sourceItems)
     {
diff --git a/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.Array.cs b/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.Array.cs
new file mode 100644
index 00000000..1b71fc57
--- /dev/null
+++ b/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.Array.cs
@@ -0,0 +1,13 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace System;
+
+partial class FlatArray
+{
+    partial class Builder
+    {
+        public static FlatArray<T>.Builder From<T>([AllowNull] params T[] source)
+            =>
+            new(source);
+    }
+}
diff --git a/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.FlatArray.cs b/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.FlatArray.cs
new file mode 100644
index 00000000..ca964104
--- /dev/null
+++ b/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.FlatArray.cs
@@ -0,0 +1,15 @@
+namespace System;
+
+partial class FlatArray
+{
+    partial class Builder
+    {
+        public static FlatArray<T>.Builder From<T>(FlatArray<T> source)
+            =>
+            FlatArray<T>.Builder.From(source);
+
+        public static FlatArray<T>.Builder From<T>(FlatArray<T>? source)
+            =>
+            FlatArray<T>.Builder.From(source);
+    }
+}
diff --git a/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.ImmutableArray.cs b/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.ImmutableArray.cs
new file mode 100644
index 00000000..3ef1332c
--- /dev/null
+++ b/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.ImmutableArray.cs
@@ -0,0 +1,17 @@
+using System.Collections.Immutable;
+
+namespace System;
+
+partial class FlatArray
+{
+    partial class Builder
+    {
+        public static FlatArray<T>.Builder From<T>(ImmutableArray<T> source)
+            =>
+            FlatArray<T>.Builder.From(source);
+
+        public static FlatArray<T>.Builder From<T>(ImmutableArray<T>? source)
+            =>
+            FlatArray<T>.Builder.From(source);
+    }
+}
diff --git a/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.List.cs b/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.List.cs
new file mode 100644
index 00000000..13b5dc31
--- /dev/null
+++ b/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.List.cs
@@ -0,0 +1,14 @@
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+
+namespace System;
+
+partial class FlatArray
+{
+    partial class Builder
+    {
+        public static FlatArray<T>.Builder From<T>([AllowNull] List<T> source)
+            =>
+            FlatArray<T>.Builder.From(source);
+    }
+}
diff --git a/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.cs b/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.cs
deleted file mode 100644
index 89d532d2..00000000
--- a/src/flatcollections-array/FlatArray/FlatArray.Builder/FlatArray.Builder.Factory.From.cs
+++ /dev/null
@@ -1,35 +0,0 @@
-using System.Collections.Generic;
-using System.Collections.Immutable;
-using System.Diagnostics.CodeAnalysis;
-
-namespace System;
-
-partial class FlatArray
-{
-    partial class Builder
-    {
-        public static FlatArray<T>.Builder From<T>([AllowNull] params T[] source)
-            =>
-            new(source);
-
-        public static FlatArray<T>.Builder From<T>(FlatArray<T> source)
-            =>
-            FlatArray<T>.Builder.From(source);
-
-        public static FlatArray<T>.Builder From<T>(FlatArray<T>? source)
-            =>
-            FlatArray<T>.Builder.From(source);
-
-        public static FlatArray<T>.Builder From<T>([AllowNull] List<T> source)
-            =>
-            FlatArray<T>.Builder.From(source);
-
-        public static FlatArray<T>.Builder From<T>(ImmutableArray<T> source)
-            =>
-            FlatArray<T>.Builder.From(source);
-
-        public static FlatArray<T>.Builder From<T>(ImmutableArray<T>? source)
-            =>
-            FlatArray<T>.Builder.From(source);
-    }
-}
diff --git a/src/flatcollections-array/FlatArray/FlatArray.T.Builder/FlatArray.Builder.Indexers.cs b/src/flatcollections-array/FlatArray/FlatArray.T.Builder/FlatArray.Builder.Indexers.cs
index 8d6f79ed..6d8b6cc2 100644
--- a/src/flatcollections-array/FlatArray/FlatArray.T.Builder/FlatArray.Builder.Indexers.cs
+++ b/src/flatcollections-array/FlatArray/FlatArray.T.Builder/FlatArray.Builder.Indexers.cs
@@ -31,8 +31,9 @@ public T this[int index]
             }
         }
 
-        // ItemRef is implemented readonly to prevent modification of FlatArray instances
+        // ItemRef are implemented readonly to prevent modification of FlatArray instances
         // initialized by calling 'MoveTo' on the Builder
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public ref readonly T ItemRef(int index)
         {
@@ -43,5 +44,10 @@ public ref readonly T ItemRef(int index)
 
             throw InnerExceptionFactory.IndexOutOfRange(index, length);
         }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public ref readonly T ItemRef(Index index)
+            =>
+            ref ItemRef(index.GetOffset(length));
     }
 }
diff --git a/src/flatcollections-array/FlatArray/FlatArray.T.Builder/FlatArray.Builder.cs b/src/flatcollections-array/FlatArray/FlatArray.T.Builder/FlatArray.Builder.cs
index 77919351..66523cb8 100644
--- a/src/flatcollections-array/FlatArray/FlatArray.T.Builder/FlatArray.Builder.cs
+++ b/src/flatcollections-array/FlatArray/FlatArray.T.Builder/FlatArray.Builder.cs
@@ -5,6 +5,9 @@ namespace System;
 
 partial struct FlatArray<T>
 {
+#if NET8_0_OR_GREATER
+    [CollectionBuilder(typeof(FlatArray.Builder), nameof(FlatArray.Builder.From))]
+#endif
     [DebuggerDisplay($"{nameof(Length)} = {{{nameof(Length)}}}")]
     public sealed partial class Builder
     {
diff --git a/src/flatcollections-array/FlatArray/FlatArray.T/Factory/Factory.Explicit.From.FlatArray.cs b/src/flatcollections-array/FlatArray/FlatArray.T/Factory/Factory.Explicit.From.FlatArray.cs
index da294659..2c6a2e7f 100644
--- a/src/flatcollections-array/FlatArray/FlatArray.T/Factory/Factory.Explicit.From.FlatArray.cs
+++ b/src/flatcollections-array/FlatArray/FlatArray.T/Factory/Factory.Explicit.From.FlatArray.cs
@@ -8,6 +8,10 @@ public static FlatArray<T> From(FlatArray<T> source)
         =>
         new(source);
 
+    public static FlatArray<T> From(FlatArray<T>? source)
+        =>
+        new(source);
+
     // TODO: Add the tests and make public
     internal static FlatArray<T> From(FlatArray<T> source, int start, int length)
     {
@@ -28,10 +32,6 @@ void InnerValidateRange()
         }
     }
 
-    public static FlatArray<T> From(FlatArray<T>? source)
-        =>
-        new(source);
-
     // TODO: Add the tests and make public
     internal static FlatArray<T> From(FlatArray<T>? source, int start, int length)
         =>
diff --git a/src/flatcollections-array/FlatArray/FlatArray.T/Factory/Factory.Explicit.From.ImmutableArray.cs b/src/flatcollections-array/FlatArray/FlatArray.T/Factory/Factory.Explicit.From.ImmutableArray.cs
index a008bdde..6d7befbe 100644
--- a/src/flatcollections-array/FlatArray/FlatArray.T/Factory/Factory.Explicit.From.ImmutableArray.cs
+++ b/src/flatcollections-array/FlatArray/FlatArray.T/Factory/Factory.Explicit.From.ImmutableArray.cs
@@ -9,6 +9,10 @@ public static FlatArray<T> From(ImmutableArray<T> source)
         =>
         new(source);
 
+    public static FlatArray<T> From(ImmutableArray<T>? source)
+        =>
+        new(source);
+
     // TODO: Add the tests and make public
     internal static FlatArray<T> From(ImmutableArray<T> source, int start, int length)
     {
@@ -36,10 +40,6 @@ void InnerValidateRange()
         }
     }
 
-    public static FlatArray<T> From(ImmutableArray<T>? source)
-        =>
-        new(source);
-
     // TODO: Add the tests and make public
     internal static FlatArray<T> From(ImmutableArray<T>? source, int start, int length)
         =>
diff --git a/src/flatcollections-array/FlatArray/FlatArray.T/FlatArray.Indexers.cs b/src/flatcollections-array/FlatArray/FlatArray.T/FlatArray.Indexers.cs
index 3fbabc6a..81bf1c59 100644
--- a/src/flatcollections-array/FlatArray/FlatArray.T/FlatArray.Indexers.cs
+++ b/src/flatcollections-array/FlatArray/FlatArray.T/FlatArray.Indexers.cs
@@ -28,4 +28,9 @@ public ref readonly T ItemRef(int index)
 
         throw InnerExceptionFactory.IndexOutOfRange(index, length);
     }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public ref readonly T ItemRef(Index index)
+        =>
+        ref ItemRef(index.GetOffset(length));
 }
diff --git a/src/flatcollections-array/FlatArray/FlatArray.csproj b/src/flatcollections-array/FlatArray/FlatArray.csproj
index 38900595..bc0fd588 100644
--- a/src/flatcollections-array/FlatArray/FlatArray.csproj
+++ b/src/flatcollections-array/FlatArray/FlatArray.csproj
@@ -18,7 +18,7 @@
     <Description>PrimeFuncPack Core.FlatArray is a core library for .NET consisting of immutable FlatArray targeted for use in functional programming.</Description>
     <RootNamespace>System</RootNamespace>
     <AssemblyName>PrimeFuncPack.Core.FlatArray</AssemblyName>
-    <Version>1.3.0-rc.1</Version>
+    <Version>1.3.0-rc.2</Version>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/flatcollections-array/FlatArray/FlatArray/FlatArray.Factory.From.FlatArray.cs b/src/flatcollections-array/FlatArray/FlatArray/FlatArray.Factory.From.FlatArray.cs
index eafbec1a..c183c066 100644
--- a/src/flatcollections-array/FlatArray/FlatArray/FlatArray.Factory.From.FlatArray.cs
+++ b/src/flatcollections-array/FlatArray/FlatArray/FlatArray.Factory.From.FlatArray.cs
@@ -6,15 +6,15 @@ public static FlatArray<T> From<T>(FlatArray<T> source)
         =>
         new(source);
 
+    public static FlatArray<T> From<T>(FlatArray<T>? source)
+        =>
+        new(source);
+
     // TODO: Add the tests and make public
     internal static FlatArray<T> From<T>(FlatArray<T> source, int start, int length)
         =>
         FlatArray<T>.From(source, start, length);
 
-    public static FlatArray<T> From<T>(FlatArray<T>? source)
-        =>
-        new(source);
-
     // TODO: Add the tests and make public
     internal static FlatArray<T> From<T>(FlatArray<T>? source, int start, int length)
         =>
diff --git a/src/flatcollections-array/FlatArray/FlatArray/FlatArray.Factory.From.ImmutableArray.cs b/src/flatcollections-array/FlatArray/FlatArray/FlatArray.Factory.From.ImmutableArray.cs
index 94003f9c..56f14e1b 100644
--- a/src/flatcollections-array/FlatArray/FlatArray/FlatArray.Factory.From.ImmutableArray.cs
+++ b/src/flatcollections-array/FlatArray/FlatArray/FlatArray.Factory.From.ImmutableArray.cs
@@ -8,15 +8,15 @@ public static FlatArray<T> From<T>(ImmutableArray<T> source)
         =>
         new(source);
 
+    public static FlatArray<T> From<T>(ImmutableArray<T>? source)
+        =>
+        new(source);
+
     // TODO: Add the tests and make public
     internal static FlatArray<T> From<T>(ImmutableArray<T> source, int start, int length)
         =>
         FlatArray<T>.From(source, start, length);
 
-    public static FlatArray<T> From<T>(ImmutableArray<T>? source)
-        =>
-        new(source);
-
     // TODO: Add the tests and make public
     internal static FlatArray<T> From<T>(ImmutableArray<T>? source, int start, int length)
         =>
diff --git a/src/flatcollections/FlatCollections/FlatCollections.csproj b/src/flatcollections/FlatCollections/FlatCollections.csproj
index 24abd215..be97a320 100644
--- a/src/flatcollections/FlatCollections/FlatCollections.csproj
+++ b/src/flatcollections/FlatCollections/FlatCollections.csproj
@@ -18,7 +18,7 @@
     <Description>PrimeFuncPack Core.FlatCollections is a set of immutable Flat collections for .NET designed for developing business applications based on functional programming.</Description>
     <RootNamespace>System</RootNamespace>
     <AssemblyName>PrimeFuncPack.Core.FlatCollections</AssemblyName>
-    <Version>1.3.0-rc.1</Version>
+    <Version>1.3.0-rc.2</Version>
   </PropertyGroup>
 
   <ItemGroup>
@@ -33,7 +33,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="PrimeFuncPack.Core.FlatArray" Version="1.3.0-rc.1" />
+    <PackageReference Include="PrimeFuncPack.Core.FlatArray" Version="1.3.0-rc.2" />
   </ItemGroup>
 
 </Project>