diff --git a/example/lib/main.dart b/example/lib/main.dart
index 9004ce8..173e113 100644
--- a/example/lib/main.dart
+++ b/example/lib/main.dart
@@ -170,6 +170,7 @@ class _MyHomePageState extends State<MyHomePage>
                         pathStrokeWidth: 10,
                         valueStrokeWidth: 10,
                         gapDegree: 60,
+                        roundCap: true,
                       ),
                     ),
                     Text("${_segmentValue / 10 * 100}%"),
@@ -200,6 +201,7 @@ class _MyHomePageState extends State<MyHomePage>
                         valueStrokeWidth: 10.0,
                         useCenter: false,
                         filled: false,
+                        roundCap: true,
                       ),
                     ),
                     Text("${_segmentValue / 10 * 100}%"),
@@ -224,6 +226,7 @@ class _MyHomePageState extends State<MyHomePage>
                         valueStrokeWidth: 10.0,
                         useCenter: true,
                         filled: true,
+                        roundCap: true,
                       ),
                     ),
                     Text("${_segmentValue / 10 * 100}%"),
diff --git a/lib/src/circular_state_progress_indicator.dart b/lib/src/circular_state_progress_indicator.dart
index 2fab24b..044caeb 100644
--- a/lib/src/circular_state_progress_indicator.dart
+++ b/lib/src/circular_state_progress_indicator.dart
@@ -24,6 +24,7 @@ class AirCircularStateProgressIndicator extends StatefulWidget {
   double _valueStrokeWidth;
   bool _filled;
   bool _useCenter;
+  bool _roundCap;
 
   /// constructor
   AirCircularStateProgressIndicator({
@@ -37,6 +38,7 @@ class AirCircularStateProgressIndicator extends StatefulWidget {
     double valueStrokeWidth = 5,
     bool filled = false,
     bool useCenter = false,
+    bool roundCap = true,
   }) {
     assert(size != null);
     assert(min >= LIMITED_MIN_VALUE);
@@ -49,6 +51,7 @@ class AirCircularStateProgressIndicator extends StatefulWidget {
     assert(valueStrokeWidth != null);
     assert(filled != null);
     assert(useCenter != null);
+    assert(roundCap != null);
     _size = size;
     //value
     _value = value;
@@ -64,6 +67,7 @@ class AirCircularStateProgressIndicator extends StatefulWidget {
     //
     _filled = filled;
     _useCenter = useCenter;
+    _roundCap = roundCap;
 
     //The strokeWidth is zero when _filled is true,
     if (_filled) {
@@ -101,8 +105,8 @@ class _CircularStateProgressIndicatorState
     return Paint()
       ..color = widget._pathColor
       ..strokeWidth = widget._pathStrokeWidth
-      ..strokeCap = StrokeCap.round
-      ..strokeJoin = StrokeJoin.round
+      ..strokeCap = widget._roundCap ? StrokeCap.round : StrokeCap.square
+      ..strokeJoin = widget._roundCap ? StrokeJoin.round : StrokeJoin.bevel
       ..style = widget._filled ? PaintingStyle.fill : PaintingStyle.stroke;
   }
 
@@ -110,8 +114,8 @@ class _CircularStateProgressIndicatorState
     return Paint()
       ..color = widget._valueColor
       ..strokeWidth = widget._valueStrokeWidth
-      ..strokeCap = StrokeCap.round
-      ..strokeJoin = StrokeJoin.bevel
+      ..strokeCap = widget._roundCap ? StrokeCap.round : StrokeCap.square
+      ..strokeJoin = widget._roundCap ? StrokeJoin.round : StrokeJoin.bevel
       ..style = widget._filled ? PaintingStyle.fill : PaintingStyle.stroke;
   }
 }
diff --git a/lib/src/linear_state_progress_indicator.dart b/lib/src/linear_state_progress_indicator.dart
index 387e8fd..a9b2222 100644
--- a/lib/src/linear_state_progress_indicator.dart
+++ b/lib/src/linear_state_progress_indicator.dart
@@ -1,6 +1,11 @@
 import 'package:ai_progress/src/progress_mixin.dart';
 import 'package:flutter/material.dart';
 
+///
+const double LINEAR_LIMITED_MIN_VALUE = 0;
+const double LINEAR_LIMITED_MAX_VALUE = 100;
+const double LINEAR_DEFAULT_VALUE = 10;
+
 /// LinearStateProgressIndicator
 ///
 // ignore: must_be_immutable
@@ -19,9 +24,9 @@ class AirLinearStateProgressIndicator extends StatefulWidget {
   /// constructor
   AirLinearStateProgressIndicator({
     @required Size size,
-    double min = 0.0,
-    double max = 100.0,
-    double value = 10,
+    double min = LINEAR_LIMITED_MIN_VALUE,
+    double max = LINEAR_LIMITED_MAX_VALUE,
+    double value = LINEAR_DEFAULT_VALUE,
     Color pathColor = Colors.white,
     Color valueColor = Colors.green,
     bool roundCap = true,
@@ -29,6 +34,17 @@ class AirLinearStateProgressIndicator extends StatefulWidget {
     double pathStrokeWidth,
     double valueStrokeWidth,
   }) {
+    assert(size != null);
+    assert(min >= LINEAR_LIMITED_MIN_VALUE);
+    assert(max <= LINEAR_LIMITED_MAX_VALUE);
+    assert(value >= min);
+    assert(value <= max);
+    assert(pathColor != null);
+    assert(valueColor != null);
+    assert(roundCap != null);
+    assert(shouldRepaint != null);
+    assert(pathStrokeWidth != null);
+    assert(valueStrokeWidth != null);
     _size = size;
     _min = min;
     _max = max;
@@ -128,7 +144,6 @@ class LinearProgressPainter extends CustomPainter with ProgressMixin {
   @override
   drawProgressPath({Canvas canvas, Paint paint, Size size}) {
     double heightCenter = size.height / 2;
-    double widthCenter = size.width / 2;
     double width = size.width;
 
     Offset startPoint = Offset(0, heightCenter);
@@ -140,8 +155,6 @@ class LinearProgressPainter extends CustomPainter with ProgressMixin {
   @override
   drawProgressValue({Canvas canvas, Paint paint, Size size}) {
     double heightCenter = size.height / 2;
-    double widthCenter = size.width / 2;
-    double width = size.width;
 
     Offset startPoint = Offset(0, heightCenter);
     Offset endPoint = Offset(_getDrawWidthValue(size: size), heightCenter);
@@ -164,7 +177,7 @@ class LinearProgressPainter extends CustomPainter with ProgressMixin {
   }
 
   double _getDrawWidthValue({@required Size size}) {
-    double drawWidthValue = size.width * (_value / _max);
+    double drawWidthValue = size.width * ((_value - _min) / (_max - _min));
 
     //range size
     drawWidthValue = drawWidthValue < 0 ? 0 : drawWidthValue;
diff --git a/lib/src/step_state_progress_indicator.dart b/lib/src/step_state_progress_indicator.dart
index 02c2c7c..8511dfb 100644
--- a/lib/src/step_state_progress_indicator.dart
+++ b/lib/src/step_state_progress_indicator.dart
@@ -4,6 +4,15 @@ import 'package:flutter/material.dart';
 /// AirStepStateProgressIndicator
 // ignore: must_be_immutable
 class AirStepStateProgressIndicator extends StatefulWidget {
+  /// Limited
+  static const int LIMITED_STEP_MIN_VALUE = 0;
+
+  /// Default values
+  static const int DEFAULT_STEP_COUNT = 10;
+  static const int DEFAULT_STEP_VALUE = 1;
+  static const double DEFAULT_STROKE_WIDTH = 5.0;
+  static const double DEFAULT_SPACE_WIDTH = 2.0;
+
   final Size size;
   final int stepCount;
   final int stepValue;
@@ -15,18 +24,32 @@ class AirStepStateProgressIndicator extends StatefulWidget {
   Color _pathColor;
   Color _valueColor;
 
+  bool _roundCap;
+
   /// constructor
   AirStepStateProgressIndicator({
     this.size,
-    this.stepCount,
-    this.stepValue,
-    double pathStrokeWidth = 5.0,
-    double valueStrokeWidth = 5.0,
-    double spaceWidth = 2.0,
+    this.stepCount = DEFAULT_STEP_COUNT,
+    this.stepValue = DEFAULT_STEP_VALUE,
+    double pathStrokeWidth = DEFAULT_STROKE_WIDTH,
+    double valueStrokeWidth = DEFAULT_STROKE_WIDTH,
+    double spaceWidth = DEFAULT_SPACE_WIDTH,
     Color pathColor = Colors.grey,
     Color valueColor = Colors.green,
+    bool roundCap = false,
   }) {
-    if (stepCount <= 0) {}
+    assert(size != null);
+    assert(stepCount != null);
+    assert(stepCount > LIMITED_STEP_MIN_VALUE);
+    assert(stepValue != null);
+    assert(stepValue >= LIMITED_STEP_MIN_VALUE);
+    assert(stepValue <= stepCount);
+    assert(pathStrokeWidth != null);
+    assert(valueStrokeWidth != null);
+    assert(spaceWidth != null);
+    assert(pathColor != null);
+    assert(valueColor != null);
+    assert(roundCap != null);
 
     //stroke width
     _pathStrokeWidth = pathStrokeWidth;
@@ -38,6 +61,9 @@ class AirStepStateProgressIndicator extends StatefulWidget {
     //color
     _pathColor = pathColor;
     _valueColor = valueColor;
+
+    //cap style
+    _roundCap = roundCap;
   }
   @override
   State<StatefulWidget> createState() {
@@ -60,6 +86,7 @@ class _StepStateProgressIndicator extends State<AirStepStateProgressIndicator> {
         spaceWidth: widget._spaceWidth,
         pathColor: widget._pathColor,
         valueColor: widget._valueColor,
+        roundCap: widget._roundCap,
       ),
     );
   }
@@ -79,6 +106,8 @@ class StepProgressPainter extends CustomPainter with ProgressMixin {
   Color _valueColor;
   Color _pathColor;
 
+  bool _roundCap;
+
   /// constructor
   StepProgressPainter._({
     @required bool shouldRepaint,
@@ -89,6 +118,7 @@ class StepProgressPainter extends CustomPainter with ProgressMixin {
     double spaceWidth,
     Color pathColor,
     Color valueColor,
+    bool roundCap,
   }) {
     //should repaint
     _shouldRepaint = shouldRepaint;
@@ -102,6 +132,7 @@ class StepProgressPainter extends CustomPainter with ProgressMixin {
     //stroke
     _pathStrokeWidth = pathStrokeWidth;
     _valueStrokeWidth = valueStrokeWidth;
+    _roundCap = roundCap;
 
     //
     _spaceWidth = spaceWidth;
@@ -155,8 +186,10 @@ class StepProgressPainter extends CustomPainter with ProgressMixin {
 
   Paint _getDrawPathPaint() {
     return Paint()
-      ..color = Colors.grey
+      ..color = pathColor
       ..style = PaintingStyle.stroke
+      ..strokeCap = _roundCap ? StrokeCap.round : StrokeCap.butt
+      ..strokeJoin = _roundCap ? StrokeJoin.round : StrokeJoin.miter
       ..strokeWidth = pathStrokeWidth;
   }
 
@@ -164,6 +197,8 @@ class StepProgressPainter extends CustomPainter with ProgressMixin {
     return Paint()
       ..color = valueColor
       ..style = PaintingStyle.stroke
+      ..strokeCap = _roundCap ? StrokeCap.round : StrokeCap.butt
+      ..strokeJoin = _roundCap ? StrokeJoin.round : StrokeJoin.miter
       ..strokeWidth = valueStrokeWidth;
   }