Channel Balance stamped with 20S 28

A home owner from scottsdale, AZ says:
My balance seems to match your 385-21.
It has "20S 28" stamped on it.
What should I order?
A user submited photo of window channel balance
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Paul from SWISCO responded:
Thanks for posting! I'm not quite sure what stamp would be best. 20S doesn't correspond to any stamp options that we have.

Could you tell me the weight of your sash? Once I know that, I can offer the best possible option for you to choose!
A home owner from Scottsdale, AZ says:
I have two windows that need new balances.
They both have the same length and ends.
The one stampe 20S 28 weighs 22.4 pounds
The other is stamped 2040P and weighs 25.1 pounds.
I hope you can identify replacements.
I guess I could move the springs from the old balances to the new ones if that would help.
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Paul from SWISCO responded:
Thanks for getting back to me so fast, Pete! For the sash that weighs 22.4 pounds, you should look at the 2040 stamp option for the S385-21. The 2040 option has a sash weight capacity of 15 through 23 pounds.

For the sash that weights 25.1 pounds, you will need the 2050 option. The 2050 option has a sash weight capacity of 23 through 27 pounds.

Please keep in mind that the weight range capacity information is based on 2 balances per sash. Balances are designed assuming friction in the jamb weather-strip will carry a portion of the sash weight. Suggested sash weights are approximate
A home owner says:
I am confused.
My unit is stamped 2040P not 2050.
Where do I enter the sash weight?
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Paul from SWISCO responded:
Thanks for getting back to us, Pete. Although the stamp is 2040, you said that the sash weight is 25.1 pounds. An S385-21 channel balance with a 2040 stamp option, as mentioned above, only supports a sash weight range of 15 through and including 23 pounds.

A stamp option of 2050, however, can carry a sash weight range of 23 through and including 27 pounds.

At this point, I would double check the weight of your sash to make sure that it is, in fact, 25.1 pounds.
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