21 12

Question

metal is 1/2" wide x 22" long  window.  I can not figure out what spring I need.  The half thatt moves up and down is 42" wide x 23 tall.

Jasmine · Accepted Answer

Thanks for posting! These window balances resemble the S351-22 and S390-22 Channel Balances. To determine which of these is the correct series, you'll need to measure the depth of the shoe.

Comparison of the S351 and S390 balance shoes.

The 21 12 stamp on the balance cannot be cross-referenced with ours. You'll need to confirm the exact weight of the window sash to determine the stamp for the replacements.

You'll find the list of stamp options and their appropriate weight ranges below the product description of the balances. They each share the same ranges.