window channel balance for non tilt window

Question

stamp picture also attached. it has 3040
And it is 31 inches. Picture of measurement also attached.
Can you help me identify the exact part. On the website, I see different series have 3040 option. I don't know which series is the right one.
Thanks!

Casey · Accepted Answer

Hello,

It looks like you have either our S351-31, with a 15-002 bottom attachment, or S390-31, 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 3040 spring strength option for your replacement balances. Thank you!

Comparison of the S351 and S390 balance shoes.