Window Balance springs

Question

Hi,

need 2 sizes pics are side by side

#1 is marked 30 4 BSI NL, length is 31", window weight is 28 lbs

#2 is marked 27 4 BSI OD, length is 28", window weight is 18 lbs

PLease recommend replacement part numbers.
Thanks

Gene

User submitted photos of a window balance.

Tom · Accepted Answer

Hey, thanks for posting. I've narrowed this down to two possible channel balance Series: either our Series 380 or our Series 385 balances.

Now, as you can see, there is only one difference between these two Series, and that is their bottom shoe. The Series 380 uses the 15-005 while the Series 385 uses the 15-004. I can't quite tell what you have based on your pictures, though. Please carefully compare their dimensions to your own hardware and see which is a better match.

Comparison of 15-004 and 15-005