I am looking to replace both coil balances on a replacement window that is in good shape other than the sash not staying open. I didn't take the coil balance out of the window (didn't have my tools with me) and the homeowner doesn't know the brand, the window is around 20 years old.
On the coil balance plastic cover? is H-431. The pocket that the balance sits in is approx. 9/16" deep and 1-1/2" wide. I calculated that the sash weighs 12.1 lbs. I'm sending photos that I hope will help.