sash balance 2970 BSI og 30

A home owner from San Diego, ca says:
I need to replace about 28 balance of different sizes. The window were manufacture by windowmaster in san diego in 1992. The number on this balance is 2970 BSI og 30. I would like to know what series they are so i can replace. I'm sending you some picture.
User submitted photo of their 2970 BSI og 30 balance.
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Mike from SWISCO responded:
You need our S385-30 channel balance with the 2970 option. Let me know if you have any further questions.
A home owner from san diego says:
I was wondering if we should order 2-balances to make sure we have the right ones
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Paul from SWISCO responded:
Well, we do recommend that you replace both balances and not just one. Replacing both window balances at the same time prevents extra wear-and-tear to the new balance, which will have to work twice as hard when paired with an old balance.
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