What does the 281000A channel balance stamp mean?

A home owner from Naperville, IL says:
March 14, 2020
I have already replaced one window with the S370 2420. It went very well!! I am replacing the rest of my windows. I have 2 1610's and 2 2220's. Those were easy to identify. However, I have 4 more windows that are 281000A. Are those just 2810's? Why the extra "00" on the number? All the other windows do not have that.

Thanks!!
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Tom from SWISCO responded:
March 17, 2020

Hello! That's actually a very peculiar stamp. I'm not sure why the manufacturer did that. It could be nothing, or it could be something extra special.

I think the best way to confirm would be to remove the sash and place it on a scale, to get its weight. Two S370-29 balances with a 2810 stamp can carry sashes weighing 7 through 12 pounds. As long as your sash falls within that range, then the 2810 is what you want.

If not, let me know and we'll find something better for your window.
25" Series 370 Channel Balance
25" Series 370 Channel Balance
S370-25
$10.82
29" Series 370 Channel Balance
29" Series 370 Channel Balance
S370-29
$11.27
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