This Extension kit has been discontinued, but you can still purchase these parts individually:
1 inch extender:2579821
4-3/4 spindle:2579831

Andersen Handle Kit Extension - Newbury - Bright Brass Parts
This is a 2 piece handle extension kit: 2579821 (1" Extender) & 2579831 (Spindle 4-3/4)
Includes 4-3/4 inch spindle and 1 inch Extension with 1/2 inch inside diameter.

This works with New Style Andersen Handles 2579611 & 2579612 Handles.
Caution - This will NOT work on the OLD STYLE Estate Handles with the 11/16 inch diameter.

NOTE 1: Old style Estate and New style Newbury are not the same size
We offer other options for Old Style Anderson and other brands
NOTE 2: Hoppe Extension # 2076412 will work on OLD Style Andersen