Window Balance Springs

Quick Learner from South Florida

Jan 25, 2026 2:23 pm

Hey there,I'm looking to replace my balance springs on my windows. They are 37" from metal end to metal end (not measuring caps) There's a stamp that says "3650 BS1F0"

5 user uploaded images

4 Replies

Emily from SWISCO

Jan 28, 2026 11:03 am

Hi there!

Thanks for reaching out to us. Take a look at the S380-37, S385-37, and S378-37. The important difference is the depth of the bottom fitting, so you'll have to measure as shown below. You can also select the 3650 stamp option.

Please let us know if you have any questions.

Comparison of the S378, S380 and S385 balance shoes.

Quick Learner from South Florida

Jan 28, 2026 11:30 am

Thank you for your reply and for pointing out the depth of the bottom fitting I believe s380 is the right one!

Emily from SWISCO

Jan 28, 2026 11:56 am

Great! I'm happy we could help. Please don't hesitate to reach out if you need anything else!