replacing channel balance

A quick learner from FL - Florida says:
October 27, 2018
Good morning!
My window are from 1987. The channel balances are all missing one thing or another. I would like to begin replacing all of them ( a mere 60!!!) They are 29" and considered 1/2" from what I can measure according to your direction yet the stamp on the side reads 28 2 ? What do I need to order please!
A quick learner from FL - Florida says:
October 27, 2018
here are pictures of the widow balance
Profile picture of Paul
Paul from SWISCO responded:
November 2, 2018

Thanks for reaching out to us. I have come up with two possible replacement balances; our S351-29 and S390-29. Depending on the measurement of your bottom balance shoe will determine which balance would make the better match for you. Please take a look at the detailed diagram below for some additional assistance. With either one you choose will go with a 2820 option. 

Comparison of 15-001 & 15-002
Comparison of 15-001 & 15-002
29" Series 351 Channel Balance
29" Series 351 Channel Balance
S351-29
$11.10
29" Series 390 Channel Balance
29" Series 390 Channel Balance
S390-29
$11.10
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