It's marked with "21C BSI EL", thank you!
Quick Learner from NY
Apr 25, 2026 11:41 pm
Hello, the balancer on one side of my double-hung window is broken, as shown in the attached photo. It bears the markings "21C BSI EL." Do you carry this specific model? Thank you!
3 user uploaded images
2 Replies
Tom from SWISCO
Apr 29, 2026 1:20 pm
Your balance appears to be a match for our Series 770. I think this may be what you want, but please look it over and see what you think.
