Help needed on Channel Balance rails

I have a pretty heavy non-tilt window that I need to replace the channel balances. This window has 4 channel balances on it currently, 1 broke the other 3 is in OK shape but I think it be best to replace all 4. The stamp on the channel balance shows 31 inches but when I measure just the metal portion it's 32 inches. Which one should I purchase?
The one rail stamp code reads: 31 5 KW CMC 7
The other stamp code reads: 31 6 KW CMC 7
Could you please confirm which channel balance would be best to select when ordering.
Thank you for the help.



We can replace these channel balances, but that stamps only tell us their spring strength. To know their identity, I need clearer views of the attachments, hooks, or nylon fittings at either end. That will help us ID what you need. See the video below.




That's a huge help, thanks. Based on what I see here, you have either our S380-32 or S385-32, 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.
One other important thing to mention is that the two balances on either side of a sash need to have the same exact stamp. In your case, one side having "31 5" and the other side having "31 6" is no good. You will need to weigh your sash on a scale and get the exact weight to confirm which stamp option to go with. We have a chart on each balance store page that you can use as a reference for this.
