Hello there. This looks like an S351-17 or S390-17 Channel Balance. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. See the diagram below for reference. Compare both with your old hardware to see what matches best.
You then have to choose a stamp option, which designates the weight range the balance is designed to support. Your old balance's stamp of 16-9 is from a rating system we do not use. To know what stamp to select, weigh the window sash the balance supports. You can then match that exact weight with one of the weight ranges listed alongside each stamp option under the product description of each and every channel balance we carry.
The video below explains more how to identify channel balances on your own, in particular to getting the length right. Let me know if you have further questions.
Gotcha, thanks for checking that sash weight. We don't currently offer a stamp option for this balance that holds that weight, but please give me a little time to look into it and see if that's something we can add for you. I'll get back to you ASAP!
