window balance

Handy Person from baltimore maryland

Nov 20, 2025 4:41 pm

it says 2965 on the balance.
the window sash weighs 40 pounds
there are 4 balances on the window.
What weight category do I need. the 65 marking seems to be a marking from an old system, and not a helpful identifier
thank you

4 user uploaded images

4 Replies

Jasmine from SWISCO

Nov 21, 2025 12:26 pm

Thanks for your post! You'll need either the S351-30 or the S390-30. To narrow down the correct match, you'll need to confirm the depth of the shoe.

For a sash weighing 40lbs, you'll need the 2970 stamp. This will support a sash weighing between 39 to 42lbs.

Comparison of the S351 and S390 balance shoes.

Handy Person from baltimore maryland

Nov 21, 2025 12:48 pm

I have 2 balances on each side of the window
Should I get balances that will work for a 40 pound window with just one on each side?

Jasmine from SWISCO

Nov 21, 2025 2:38 pm

Apologies for missing that very important detail. You'll need to use (4) of the 2930 stamp options. A pair of these will support 16 to 23lbs.

Please let me know if you have any additional questions!