Window sash balance

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 length of the metal channel excluding the nylon attachments should measure 35 inches long. 

I see two balances with a 3440 stamp and one balance with 3420 stamp. Are these from different sized windows? The balances should have the same stamp number on both sides per sash which indicates the strength of the spring to support the window when opened. 

Comparison of the S378, S380 and S385 balance shoes.