26 4 GU CMC 4 window spring

Hi there- thanks for posting! 

I was able to narrow what you have down to two options. You either have our Series 380 or our Series 385 channel balance. The difference lies in the depth of the shoe. The series 385 balance has a 15-004 shoe, which is 1-3/32” deep while the Series 380 balance has a 15-005 shoe, which is 1” deep. 

Please reference the below photo to see exactly how to measure the depth of your shoe to determine which series you have.

You'll want to choose the 27" length of the correct series and the 2640 "option" at checkout. 

Comparison of 15-004 and 15-005

If you have any questions at all please don’t hesitate to reach out to us.