Balance spring

Thanks for reaching out! The piece you have here is the 15-102 Double Side Load Carrier. To confirm this is the right fit for your window, carefully look over the dimensions below.

Alternate view of 15-102

Alternate view of 15-102

This carrier is compatible with the Series 145 Balance Spring. To determine the springs needed to repair your assembly, you'll need to obtain the exact weight of your sash. 

Unfortunately, we would not be able to calculate the weight of the sash based on the size. That measurement does not account for the weight of glass panes in addition to the frame.