Need help identifying balance

Thanks for writing in. This looks like either an S380-27 or S385-27. The only difference between these two balances is the depth of the bottom nylon shoe, or the measurement from heel to toe. See the illustration below for reference. Compare both balances to your old hardware to see what matches best.

Comparison of the S378, S380 and S385 balance shoes.

Once you know what balance you have, you have to choose a stamp option. This designates the balance's strength. Your old balance's stamp of 26-9 is from a rating system we do not use. To know what stamp to select, weigh the window sash that these balances support. You can then match that exact weight with one of the weight ranges listed alongside each stamp option under the product description on either the S380-27 or S385-27 shop page.