Balancers

With this combination of attachments, you could have either an S380 or S385 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. The 2950 stamp indicates that you need a 30" balance as you mentioned with a 2950 strength option, but your other stamp is a bit unusual. I would recommend double-checking the other balance in that window to make sure it has the same stamp. If so, you'll 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 the S378, S380 and S385 balance shoes.