window balance

Thanks for posting. I am afraid those stamps only tell us the strength of the balances. They do not tell us their identity. To know what kind of balance you need, we'll need to see pictures of the nylon fittings or attachments at both ends of the metal channel. The combination of attachments used is what determines the kind of balance you have. From there we'll do our best to ID what you need. 

Thanks for getting back to me, that's perfect. You have either our S380-27 or S385-27. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. Compare the diagram below with your old balances to see what matches best. In either case, for the stamp option, choose 2640, which is in accordance with your old balances' 26-4 stamp. Let me know if you have further questions!

Comparison of the S378, S380 and S385 balance shoes.