Window Balance BSI 27 4 00

Hello Dave,

With this combination of attachments, you could have either a Series 380 or Series 385 channel balance. You need to measure as shown below. The Series 380 has a 1" bottom attachment, and the Series 385 has a 1-3/32" attachment. It looks like you'll need the S385-28 balance. You'll also need to weigh your sash to determine which option you'll need. There is a chart on the product page that explains how to choose your option based on the sash weight.

Thank you and let us know if you have any other questions or concerns.

Comparison of 15-004 and 15-005

In that case, you'll need our S385-28 channel balance with a 2740 option. 

Thank you!