27 inch window balancer

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 2630 spring strength option for your balances. 

Comparison of the S351 and S390 balance shoes.

For the difference between the two shoes, take a closer look at the diagram. The depth measurement of the shoe is slightly different from one another. You will need to measure the depth of your bottom balance shoe the way it is shown in the diagram to determine which Series channel balance would make the best replacement. Although your nylon fittings show some differences, it is very minimal and can still be replaced by one of the options we mentioned based on measurements. 

Your balance is slightly different in shape. However, we still feel one of these two balance replacements will work. Since the depth of your bottom balance shoe measures 1-1/8", then you want to focus your attention to the Series 390.