window balance stamp

A handy person from Virginia beach, VA says:
September 29, 2020
Hello,

I'm replacing the balances on a few of my Gapco windows. I measured the old ones and matched the part up to the 19" series 351. However the stamp on my old ones is 2820, which I'm not seeing as an option. Which product should I be using?
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Bob from SWISCO responded:
October 2, 2020

If the metal channel, not including the nylon fittings, is absolutely 19" long, then a stamp code of 2820 would be very unusual. It's possible these balances were cut down to size to fit your windows. In any event, I would obtain the exact weight of the window sash. You can then match that exact weight with one of the weight ranges listed alongside each stamp option in the S351-19 product description. 
A handy person from Virginia beach, VA says:
October 2, 2020
Sounds like a good idea. Thanks!
19" Series 351 Channel Balance
19" Series 351 Channel Balance
S351-19
$9.34
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