20 4 ET CMC 4 channel ballance
21 inches long metal, measured twice
what replacement part do I need to buy
The numbers stamped on the balance only indicates the spring strength. We will need to see photos of the balance completely removed from the window in order to make a recommendation. Thank you.
Hello,
From your photo, It appears that you have either our S385-21 or S395-21. The difference between the two is that the top and bottom attachments have nylon wings on the S385, while only the top attachment has the one the S395. It's hard to tell from your photo whether you have the S395 or the tabs just broke off of the bottom attachment.
You may want to check a window with balances that are in slightly better shape to confirm. In either case, the spring strength option for the balances will be (2040). Thanks for posting!