Sash balance

Thanks for writing in. Confirm that the metal channel, not including the nylon fittings, is 21" long. If so, see our S380-21 or S385-21. The only difference between these two balances is the depth of the bottom nylon shoe, so compare both with your old hardware to see what matches best. Your balance's stamp option of 20 9 is from an older rating system we do not use. To know what stamp option to select, weigh your window sash. You can then match that exact weight with one of the weight ranges listed alongside each stamp option on the product page.