diff --git a/src/chonkie/refinery/base.py b/src/chonkie/refinery/base.py
index a26c62d..7896f6a 100644
--- a/src/chonkie/refinery/base.py
+++ b/src/chonkie/refinery/base.py
@@ -1,5 +1,5 @@
 from abc import ABC, abstractmethod
-from typing import List
+from typing import List, Union
 
 from chonkie.types import Chunk
 
@@ -23,6 +23,10 @@ def __init__(self, context_size: int = 0) -> None:
     def refine(self, chunks: List[Chunk]) -> List[Chunk]:
         """Refine the given list of chunks and return the refined list."""
         pass
+    
+    def refine_batch(self, chunks_batch: List[List[Chunk]]) -> List[List[Chunk]]:
+        """Refine the given list of chunks and return the refined list."""
+        return [self.refine(chunks) for chunks in chunks_batch]
 
     @classmethod
     @abstractmethod
@@ -34,6 +38,29 @@ def __repr__(self) -> str:
         """Representation of the Refinery."""
         return f"{self.__class__.__name__}(context_size={self.context_size})"
 
-    def __call__(self, chunks: List[Chunk]) -> List[Chunk]:
-        """Call the Refinery."""
-        return self.refine(chunks)
+    def __call__(self, chunks: Union[List[Chunk], List[List[Chunk]]]) -> Union[List[Chunk], List[List[Chunk]]]:
+        """Call the Refinery.
+        
+        Args:
+            chunks: Either a list of Chunks or a list of lists of Chunks
+            
+        Returns:
+            Refined chunks in the same format as input
+            
+        Raises:
+            ValueError: If input type is not a list of Chunks or list of lists of Chunks
+        
+        """
+        # If chunks is not a list or is empty, return chunks
+        if not isinstance(chunks, list) or not chunks:
+            return chunks
+        
+        # Check if it's a list of Chunks
+        if isinstance(chunks[0], Chunk):
+            return self.refine(chunks)
+        
+        # Check if it's a list of lists of Chunks
+        if isinstance(chunks[0], list) and chunks[0] and isinstance(chunks[0][0], Chunk):
+            return self.refine_batch(chunks)
+        
+        raise ValueError("Invalid input type for Refinery: must be List[Chunk] or List[List[Chunk]]")
diff --git a/src/chonkie/refinery/overlap.py b/src/chonkie/refinery/overlap.py
index b823ef2..7b4d248 100644
--- a/src/chonkie/refinery/overlap.py
+++ b/src/chonkie/refinery/overlap.py
@@ -50,6 +50,9 @@ def __init__(
         else:
             # Without tokenizer, must use approximate method
             self.approximate = True
+        
+        # Average number of characters per token
+        self._AVG_CHAR_PER_TOKEN = 7
 
     def _get_refined_chunks(
         self, chunks: List[Chunk], inplace: bool = True
@@ -168,7 +171,7 @@ def _suffix_overlap_token_exact(self, chunk: Chunk) -> Optional[Context]:
             return None
 
         # Take 6x context_size characters to ensure enough tokens
-        char_window = min(len(chunk.text), self.context_size * 6)
+        char_window = min(len(chunk.text), self.context_size * self._AVG_CHAR_PER_TOKEN)
         text_portion = chunk.text[:char_window]
 
         # Get exact token boundaries