Replace window balance

Question

Please assist in identifying my window channel balance for replacement. The stamp on my existing window channel balance is B.S.I.2410A. See attached photos.
I have (4) each to replace.

Bob · Accepted Answer

Thanks for writing in. This looks like either our S351-25 or S390-25. The only difference between these two balances is the depth of the bottom nylon shoe, so compare both with your old hardware to see what matches best. See the diagram below as reference. For a stamp option go with 2410.

Comparison of the S351 and S390 balance shoes.