Window balance spring

Question

the metal part is 15 inches long & 1/2 inch wide.  But I can't tell which one to select to match the plastic top & bottom.  thank you!

Bob · Accepted Answer

Thanks for posting. This looks like either a S380-15 or S385-15 Channel Balance, depending on the 'depth' of the bottom nylon shoe. See below. In either case, for a stamp option choose 1440.

Comparison of the S378, S380 and S385 balance shoes.