BSI Sash balance # 28-4

Hi there!

With this combination of attachments, you could have either an S380-29 or S385-29 channel balance. You’ll need to measure as shown below. The Series 380 has a 1" bottom attachment, and the Series 385 has a 1-3/32" attachment. You will also need a spring strength option of 2840.

Pricing can be found on the S380 and S385 respective store pages as well. 

Comparison of the S378, S380 and S385 balance shoes.