There are no numbers on this part.

A quick learner from CT says:
July 7, 2022

There are no numbers on this part. This part holds the 32 inch balances to the top.

It measures links wise 2 1/2 inches. By 6/16

The kind of windows I have are Acorn.

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Casey from SWISCO responded:
July 12, 2022

Hello,

Acorn parts can sometimes be hard to come but we'd be happy to look into this for you to confirm if it is still available. If you could show us a photo of the part installed, as well as elaborate on its function, we can go from there. Thank you. 
A quick learner from CT says:
July 12, 2022
The screw goes through this plastic piece and holds the top of the balance in place. I think it's used to keep The balance centered in the channel.
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Casey from SWISCO responded:
July 12, 2022

Thanks for getting back to us. The closest option that we carry would be the 55-046 Acorn sash stop but it is a different style. We can't guarantee that this would work but look over the specifications to see if you might be able to use this part for your application. Thanks for posting. 
Acorn Sash Stop
Acorn Sash Stop
55-046
$1.52
Acorn Window Stop
Acorn Window Stop
55-063
$1.52
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