Need part number for small window

Hello,

It looks like you have either our S351, with a 15-002 bottom attachment, or S390, with a 15-001 bottom attachment. Take a look at the image below to determine which balance you'll need. You'll also need an 1110 spring strength option for your replacement balances. I would recommend double checking the length of your metal channel, not including the end attachments, since your stamp indicates that the length would be 12". Thank you!

Comparison of the S351 and S390 balance shoes.