Need part identified

Hello,

It looks like you have either our S351-29, with a 15-002 bottom attachment, or S390-29, with a 15-001 bottom attachment. Take a look at the image below to determine which balance you'll need. You'll also need a 2830 spring strength option for your replacement balances. Thank you!

Comparison of the S351 and S390 balance shoes.

The photo of your original balance shows a 2830 stamp, which means you'll need the corresponding 2830 strength option to support a 16 to 23 lbs window sash.