Non tilting window balance for a 38-1/2" x 36" double plain aluminum window

Question

Need qty (2) window block n tackle window balances. Overall metal channel length 34" and channel width 1/2".  No roller at the bottom and only legible markings "3340", "cj" and "BSI(?)" See attached photos. Any suggestions would be greatly appreciated

Jasmine · Accepted Answer

Thanks for posting! I'll need to see a photo of the existing balances to confirm the correct series. The stamp from the balance only tells us the weight range it may be able to support but I cannot use it to identify the series.

Take a look at the video tutorial below for reference.