2 different Sash Balancers

Question

I'm trying to replace these with new ones. Can you tell me which one to get please? i hope they are all the same because i need 4 of them. Thanks

Regard,
Marvin

User submitted image of their window hardware.

Paul · Accepted Answer

Hello! These two balances are not the same. Do they go on the same window? If so, that might raise some problems. The first one, which appears to be older, is stamped "837." This corresponds to our 24-837 Andersen sash balance, unsurprisingly.

The second, which looks somewhat newer, is stamped "7#31." This stamp relates to our 24-737 Andersen sash balance.

According to my records, these balances are used on windows of the same height, however the 24-837 window might be somewhat wider, requiring a stronger balance.