Window balance springs

Handy Person from Thousand Oaks, Calif.

Sep 4, 2026 3:09 pm

I have 20 windows that need both balance springs replaced. The only identifier numbers I could find are "30 B.S.I. OG".

5 user uploaded images

3 Replies

Handy Person from Thousand Oaks, Calif.

Sep 4, 2026 3:17 pm

The metal case is 30 7/8" long. This does s not include the plastic clips length at each end of the metal case.

Bob from SWISCO

Sep 5, 2026 8:03 pm

Hey there. Looks like you have an S380-31 or S385-31 Channel Balance, depending on the shoe depth. See below. For a stamp option choose 3030.

Comparison of the S378, S380 and S385 balance shoes.