Original Weathershield double hung windows from 1978 house

A home owner from Cascade twp mi says:
Need balances for 2 different size windows. Markings on the 37 inch balance says 3640., 25 inch says 2430. I believe that your 350 series should work. Please confirm so I can order .
Thanks.
User submitted photos of a window balance.
Profile picture of Tom
Tom from SWISCO responded:
Thanks for contacting us. I don't think the Series 350 is what you want. The bottom shoe for that balance is the 15-004, which has wings. Yours does not appear to have wings. See our Series 390 instead. Carefully go over the pictures and measurements for the nylon caps to confirm.
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