diff --git a/sparrow-py/pysrc/sparrow_py/__init__.py b/sparrow-py/pysrc/sparrow_py/__init__.py
index f7a4a4a9d..b6500c005 100644
--- a/sparrow-py/pysrc/sparrow_py/__init__.py
+++ b/sparrow-py/pysrc/sparrow_py/__init__.py
@@ -4,6 +4,7 @@
 from typing import Union
 
 from . import sources
+from ._execution import ExecutionOptions
 from ._expr import Expr
 from ._result import Result
 from ._session import init_session
@@ -21,12 +22,13 @@ def record(fields: Dict[str, Expr]) -> Expr:
 
 
 __all__ = [
+    "ExecutionOptions",
     "Expr",
     "init_session",
     "record",
-    "Window",
+    "Result",
     "SinceWindow",
     "SlidingWindow",
     "sources",
-    "Result",
+    "Window",
 ]
diff --git a/sparrow-py/pysrc/sparrow_py/_execution.py b/sparrow-py/pysrc/sparrow_py/_execution.py
new file mode 100644
index 000000000..653c7cb42
--- /dev/null
+++ b/sparrow-py/pysrc/sparrow_py/_execution.py
@@ -0,0 +1,16 @@
+from dataclasses import dataclass
+from typing import Optional
+
+
+@dataclass
+class ExecutionOptions:
+    """Execution options for a query.
+
+    Attributes
+    ----------
+    row_limit : Optional[int]
+        The maximum number of rows to return.
+        If not specified (the default), all rows are returned.
+    """
+
+    row_limit: Optional[int] = None
diff --git a/sparrow-py/pysrc/sparrow_py/_expr.py b/sparrow-py/pysrc/sparrow_py/_expr.py
index 2f2a389a2..76149b8a2 100644
--- a/sparrow-py/pysrc/sparrow_py/_expr.py
+++ b/sparrow-py/pysrc/sparrow_py/_expr.py
@@ -14,6 +14,8 @@
 import sparrow_py as kt
 import sparrow_py._ffi as _ffi
 
+from ._execution import ExecutionOptions
+
 
 #: The type of arguments to expressions.
 Arg = Union["Expr", int, str, float, None]
@@ -323,7 +325,7 @@ def show(self, limit: int = 100) -> None:
 
     def run(self, row_limit: Optional[int] = None) -> pd.DataFrame:
         """Run the expression."""
-        options = _ffi.ExecutionOptions(row_limit=row_limit)
+        options = ExecutionOptions(row_limit=row_limit)
         batches = self._ffi_expr.execute(options).collect_pyarrow()
         schema = batches[0].schema
         table = pa.Table.from_batches(batches, schema=schema)
@@ -368,8 +370,8 @@ def _aggregation(
     if window is None:
         return Expr.call(op, *args, input, None, None)
     elif isinstance(window, kt.SinceWindow):
-        return Expr.call(op, *args, input, window._predicate, None)
+        return Expr.call(op, *args, input, window.predicate, None)
     elif isinstance(window, kt.SlidingWindow):
-        return Expr.call(op, *args, input, window._predicate, window._duration)
+        return Expr.call(op, *args, input, window.predicate, window.duration)
     else:
         raise NotImplementedError(f"Unknown window type {window!r}")
diff --git a/sparrow-py/pysrc/sparrow_py/_ffi.pyi b/sparrow-py/pysrc/sparrow_py/_ffi.pyi
index 184542a11..ca1b56244 100644
--- a/sparrow-py/pysrc/sparrow_py/_ffi.pyi
+++ b/sparrow-py/pysrc/sparrow_py/_ffi.pyi
@@ -3,15 +3,13 @@ from typing import Optional
 from typing import Sequence
 
 import pyarrow as pa
-from sparrow_py.udf import Udf
+
+from ._execution import ExecutionOptions
+from .udf import Udf
 
 class Session:
     def __init__(self) -> None: ...
 
-class ExecutionOptions(object):
-    def __init__(self, row_limit: Optional[int] = None) -> None: ...
-    row_limit: Optional[int]
-
 class Execution(object):
     def collect_pyarrow(self) -> List[pa.RecordBatch]: ...
 
diff --git a/sparrow-py/pysrc/sparrow_py/_windows.py b/sparrow-py/pysrc/sparrow_py/_windows.py
index 14437016c..ae27614f0 100644
--- a/sparrow-py/pysrc/sparrow_py/_windows.py
+++ b/sparrow-py/pysrc/sparrow_py/_windows.py
@@ -1,25 +1,45 @@
-import sparrow_py
+from dataclasses import dataclass
 
+from ._expr import Expr
 
+
+@dataclass(frozen=True)
 class Window(object):
     """Base class for window functions."""
 
-    def __init__(self) -> None:
-        pass
-
 
+@dataclass(frozen=True)
 class SinceWindow(Window):
-    """Window since the last time a predicate was true."""
+    """
+    Window since the last time a predicate was true.
+
+    Aggregations will contain all values starting from the last time the predicate
+    evaluated to true (inclusive).
 
-    def __init__(self, predicate: "sparrow_py.Expr") -> None:
-        super().__init__()
-        self._predicate = predicate
+    Parameters
+    ----------
+    predicate : Expr
+        The predicate to use for the window.
+        Each time the predicate evaluates to true the window will be cleared.
+    """
 
+    predicate: Expr
 
+
+@dataclass(frozen=True)
 class SlidingWindow(Window):
-    """Sliding windows where the width is a multiple of some condition."""
+    """
+    Window for the last `duration` intervals of some `predicate`.
+
+    Parameters
+    ----------
+    duration : int
+        The number of sliding intervals to use in the window.
+
+    predicate : Expr
+        The predicate to use for the window.
+        Each time the predicate evaluates to true the window starts a new interval.
+    """
 
-    def __init__(self, duration: int, predicate: "sparrow_py.Expr") -> None:
-        super().__init__()
-        self._duration = duration
-        self._predicate = predicate
+    duration: int
+    predicate: Expr
diff --git a/sparrow-py/src/execution.rs b/sparrow-py/src/execution.rs
index 91b5c3fb1..405282f5f 100644
--- a/sparrow-py/src/execution.rs
+++ b/sparrow-py/src/execution.rs
@@ -4,13 +4,6 @@ use sparrow_session::Execution as RustExecution;
 
 use crate::error::{Error, ErrorContext};
 
-#[pyclass]
-#[derive(Default)]
-pub(crate) struct ExecutionOptions {
-    #[pyo3(get, set)]
-    pub(crate) row_limit: Option<usize>,
-}
-
 /// Kaskada execution object.
 #[pyclass]
 pub(crate) struct Execution(Option<RustExecution>);
@@ -36,19 +29,3 @@ impl Execution {
         Ok(results)
     }
 }
-
-#[pymethods]
-impl ExecutionOptions {
-    #[new]
-    fn new(row_limit: Option<usize>) -> Self {
-        Self { row_limit }
-    }
-}
-
-impl ExecutionOptions {
-    pub(crate) fn to_rust_options(&self) -> sparrow_session::ExecutionOptions {
-        sparrow_session::ExecutionOptions {
-            row_limit: self.row_limit,
-        }
-    }
-}
diff --git a/sparrow-py/src/expr.rs b/sparrow-py/src/expr.rs
index 9bbe9cff0..a97c2aff4 100644
--- a/sparrow-py/src/expr.rs
+++ b/sparrow-py/src/expr.rs
@@ -1,5 +1,5 @@
 use crate::error::Error;
-use crate::execution::{Execution, ExecutionOptions};
+use crate::execution::Execution;
 use crate::session::Session;
 use arrow::pyarrow::ToPyArrow;
 use pyo3::exceptions::{PyRuntimeError, PyValueError};
@@ -73,11 +73,9 @@ impl Expr {
         self.session.clone()
     }
 
-    fn execute(&self, options: Option<&ExecutionOptions>) -> Result<Execution, Error> {
+    fn execute(&self, options: Option<&PyAny>) -> Result<Execution, Error> {
         let session = self.session.rust_session()?;
-        let options = options
-            .map(ExecutionOptions::to_rust_options)
-            .unwrap_or_default();
+        let options = extract_options(options)?;
         let execution = session.execute(&self.rust_expr, options)?;
         Ok(Execution::new(execution))
     }
@@ -121,3 +119,15 @@ impl Arg {
         }
     }
 }
+
+fn extract_options(options: Option<&PyAny>) -> Result<sparrow_session::ExecutionOptions, Error> {
+    match options {
+        None => Ok(sparrow_session::ExecutionOptions::default()),
+        Some(options) => {
+            let py = options.py();
+            Ok(sparrow_session::ExecutionOptions {
+                row_limit: options.getattr(pyo3::intern!(py, "row_limit"))?.extract()?,
+            })
+        }
+    }
+}
diff --git a/sparrow-py/src/lib.rs b/sparrow-py/src/lib.rs
index 97334b3e1..1495b6326 100644
--- a/sparrow-py/src/lib.rs
+++ b/sparrow-py/src/lib.rs
@@ -18,7 +18,6 @@ fn ffi(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     m.add_class::<expr::Expr>()?;
     m.add_class::<table::Table>()?;
     m.add_class::<execution::Execution>()?;
-    m.add_class::<execution::ExecutionOptions>()?;
 
     Ok(())
 }