replacement window balance

Question

Spring is broken as well as the bar that holds the spring at the top. Length measuring only metal = 20 7/8"; width is 1/2". Markings on metal are "20 C" and "B.S.I.". Please advise on which balance I should be ordering. Thank you.

Tom · Accepted Answer

Thanks for your photos. Based on what I see here, you have either our S351-21 or S390-21, depending on the depth of the bottom shoe. That's the only difference between them. I recommend measuring your shoe and referring to our dimensions to confirm the best match.

You should also triple check the length of the metal channel. Based on the stamp, this should be 21" long, not 20-7/8". That's not a length we can supply, so just something to be mindful of moving forward.

Comparison of the S351 and S390 balance shoes.