Window Balance

Thanks for posting. That code actually tells us the strength of the balance, which is important to know, but not its identity. The identity of a channel balance is determined by those nylon fittings on either end. Based on the shape of those fittings, I can tell you that you have either an S380-21 or S385-21. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. See the diagram below for reference. Compare both with your old hardware to see what matches best. In either case, for the stamp option (which designates the strength), choose 2030, which accords with your old balance's stamp. Let me know if you have further questions.

Comparison of the S378, S380 and S385 balance shoes.

Perfect! Glad I could help, and let us know if you have any other questions.