21 12bsi marking channel balance

Question

I am in need of two Channel balances. The markings are as shown in the photos 21 12BSI  and the channel itself measures 22 inches Not including the end pieces. Thank you for your time.

Casey · Accepted Answer

Hello,

It looks like you have either our S351-22, with a 15-002 bottom attachment, or S390-22, with a 15-001 bottom attachment. Take a look at the image below to determine which balance you'll need.

You'll also need to weigh your sash to determine which option you'll need. There is a chart on the product page that explains how to choose your option based on the sash weight. Thank you!

Comparison of the S351 and S390 balance shoes.