IWC 26" Channel Balance with no markings

Hello! Based on your photos, I was able to narrow down the list of possible replacement balances to just two choices: either our S390-26 or S351-26. The only difference between them is the depth of the bottom fitting, so you'll have to measure yours to confirm the better match.

Since there is no stamp on your old balance, you'll have to weigh your sash on a scale to confirm which option to go with. There's a chart on both the S390-26 and S351-26 store pages that tells you how much weight each option supports. Once you have your sash weight, all you have to do is reference that chart.