Window retractors

Hello, thank you for posting,

With this combination of attachments, you could have either an S378, S380 or S385 channel balance. You’ll need to measure as shown below. The main difference is the depth of the bottom shoe.

The 27 4 number is the main marking on the balances that indicate the strength of the spring. You will need a 28" balance with a 2740 stamp option that can support a 19-26 pound window sash. Please review and let me know if you have any additional questions. 

Comparison of the S378, S380 and S385 balance shoes.