Block/Tackle sash balance?

A home owner from North Augusta, SC says:
January 5, 2024
I'm not sure what it's called, this from one side of the window, I'll assume the two sides are the same, but I'm not sure. I don't want to try to open the window in case it comes crashing down without this thing.

The home was built in 1999, if that helps. The part says 2800, then a sideways BS1 or BSI, then LC or LG.
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Casey from SWISCO responded:
January 5, 2024

Hello,

I would recommend starting by comparing the specifications of the S770-28 channel balance to an undamaged version of your assembly. You'll also need to confirm that the metal channel measures exactly 28" long. 

Close up view of the Series 770 balance top.
Close up view of the Series 770 balance top.

Close up view of the Series 770 balance bottom.
Close up view of the Series 770 balance bottom.

Your stamp code does not correspond to any of our strength options for the S770, so you'll also need to weigh your window sash to determine the correct option for your replacement balances. There is a chart on the product page that explains how to choose your option based on the sash weight. Take a look and let us know if you have any other questions. 
28" Series 770 Balance
28" Series 770 Balance
S770-28
$12.70
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