Need balancers
Hello!
Your balance appears to match either our S390-22 or S351-22, depending on the depth of your bottom fitting. Measure as shown below to see which one matches best. Your stamp doesn't correspond with any of our options so you will need to weigh your sash on a scale and refer to the chart under the product description on the S390 and S351 store pages to determine the appropriate spring strength option for your balance.
In that case, I would recommend the 2170 strength option. A pair of balances with this stamp will support a sash weighing 34 to 37 pounds.
32 pound sash
If your bottom shoe measures 1-1/8" deep, you would want the Series 390. If you have the S390-22 and your sash weighs 32 pounds, see the 2165 strength option for a sash weighing 30 to 34 pounds.