Window Balance

Thanks for the photos. It appears you have S390-16 with a 1-1/8" shoe. To determine the stamp needed for your balance, you'll need to check the metal channel of your balance. If the stamp does not match the options shown in the catalog you'll need to obtain the exact weight of the window and use the chart below the product description to select the stamp according to the weight ranges.

Comparison of the S351 and S390 balance shoes.