Hi,
I am trying to match my window balance springs. The balance springs are 1/2" wide and 30" long (length of the metal housing without the plastic top or bottom shoe). Based upon my search on your website, I come up with a Series 380 and probably with the 2930 option based on the markings on the original. My only concern is the top plastic piece. It is a bit different than yours although it looks like it would work - I'm just not sure. Please see the photos attached and let me know what you think. If you need more info, please let me know.
Thank you,
Russell