Window channel balance

Question

I have two types of balances. They are marked 28D and 22E. How does the letter stamp correlate to the number stamp?

Thank you.

User submitted photos of a window balance.

Tom · Accepted Answer

A stamp of 28D usually corresponds to our 2840 option, while a stamp of 22E would correspond to our 2250 option. It basically goes in the same order as the alphabet: A=10, B=20, C=30, D=40, E=50, and so on. You can also weigh your sash on a scale to be 100% sure.