American craftsman window

Hello there. This looks a 15-087 Pivot Shoe, which uses Series 180 Coil Balances. These pieces are sold separately. For the coil springs, you need to select a spring weight. This designates the weight an individual coil can support. There should be a stamp on the coil itself that indicates the right spring weight--with this Series, we find the stamps on the shoe itself are not necessarily accurate and shouldn't be used. If there is no stamp on the spring, or you are unsure, give me the exact weight of the window sash that this system supports, and I'd be happy to calculate the spring weights needed.

Series 180 coil balance diagram