Jasmine from SWISCO responded:
October 18, 2023
Thanks for reaching out! Your channel balances look like they could be either the S351-27 with a 1" shoe or the S390-27 with a 1-1/8" shoe. To determine which series is needed for your window, look over the dimensions from the diagram below to confirm the depth of your bottom shoe. You'll need to select the 2630 stamp. Comparison of the S351 and S390 balance shoes.
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