Window balancer single hung, has a mark 3440

Hello,

With this combination of attachments, you could have either the S378-35, S380-35, or S385-35 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'll also need 3440 spring strength options for your replacement balances. Thank you and let us know if you have any other questions or concerns.

Comparison of the S378, S380 and S385 balance shoes.