non-tilt balance identification

A home owner from Rancho Bernardo, San Diego, Zip 92128 says:
May 9, 2020
Hi , I can't find the correct size of replacement balance for my windows.
The ones I am to replace have stamped numbers 3390 and 35. The metal piece does however only measure 34 inches, I measure exactly 35 with the plastic inserts. The metal has hemmed edges. I need 4 pieces for two windows.
Thanks for your help.
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Casey from SWISCO responded:
May 12, 2020

Hello,

It looks like you have either our S351, with a 15-002 bottom attachment, or S390, with a 15-001 bottom attachment. Take a look at the image below to determine which balance you'll need. Keep in mind that when determining length, you only measure the metal channel, not including the end attachments. 

You'll also need to weigh your window sash since the 3390 stamp is an outdated system. Once you know which balance and length you need, you can follow the chart under the product description to choose the correct spring strength option. Thank you! 

Comparison of the S351 and S390 balance shoes.
Comparison of the S351 and S390 balance shoes.
A home owner from Rancho Bernardo, San Diego, Zip 92128 says:
May 18, 2020
I received the parts and they are a perfect fit and easy to install. Thank you very much for the great customer service.
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Casey from SWISCO responded:
May 19, 2020

I'm happy to hear that the S390 balances that you ordered worked out for you! Please let us know if there are any other projects we can help with. 
35" Series 390 Channel Balance
35" Series 390 Channel Balance
S390-35
$12.05
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