What does a stamped B mean?

Question

I'm replacing some balances on a 22 1/2 x 32 window. They are stamped 29B. It's a 30 inch balance but what weight is "B"? Also, it has winged top and shoe.

Bob · Accepted Answer

Sounds like you have either an S380-30 or S385-30, depending on the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. Compare both with your old hardware to see what matches best. That 29B refers to the stamp option, or the strength of the spring inside the balance. It conforms to our stamp option of 2920, which is what you'd choose for the replacement balance.