Window balances

Thanks for reaching out to us. Based on these photos, I recommend either the S380-12 or S385-12 depending on the depth of the bottom fitting. The stamp, however, doesn't match up to any of the listed options. You'll have to weigh the window sash on a scale and refer to the chart under the product description on the S380-12 and S385-12 store pages to determine the accordant stamp. 

Comparison of the S380 and S385 balance shoes.