Window Channel balance
Thanks for posting. I'm sure we can help, but I need to see the attachment on the other end of the metal channel as well. The combination of top and bottom fittings is what determines the kind, or Series, balance you have. Once I see that top fitting I should be able to narrow this down for you. Many thanks.
Thanks for getting back to me, that's perfect. I believe this is either an S380-21 or S385-21. 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. Compare both with your old hardware to see what matches best. For a new stamp option, choose 2020.