diff --git a/python/aare/ClusterFinder.py b/python/aare/ClusterFinder.py
index 99bcc5f..5509e51 100644
--- a/python/aare/ClusterFinder.py
+++ b/python/aare/ClusterFinder.py
@@ -1,16 +1,8 @@
-
-# from ._aare import ClusterFinder_Cluster3x3i, ClusterFinder_Cluster2x2i, ClusterFinderMT_Cluster3x3i, ClusterFinderMT_Cluster2x2i, ClusterCollector_Cluster3x3i, ClusterCollector_Cluster2x2i
-
-
-# from ._aare import ClusterFileSink_Cluster3x3i, ClusterFileSink_Cluster2x2i
-
 from . import _aare
 import numpy as np
 
 _supported_cluster_sizes = [(2,2), (3,3), (5,5), (7,7), (9,9),]
 
-# def _get_class()
-
 def _type_to_char(dtype):
     if dtype == np.int32:
         return 'i'
@@ -74,11 +66,11 @@ def ClusterFileSink(clusterfindermt, cluster_file, dtype=np.int32):
     return cls(clusterfindermt, cluster_file)
 
 
-def ClusterFile(fname, cluster_size=(3,3), dtype=np.int32):
+def ClusterFile(fname, cluster_size=(3,3), dtype=np.int32, chunk_size = 1000):
     """
     Factory function to create a ClusterFile object. Provides a cleaner syntax for
     the templated ClusterFile in C++.
     """
 
     cls = _get_class("ClusterFile", cluster_size, dtype)
-    return cls(fname)
+    return cls(fname, chunk_size=chunk_size)