Casey from SWISCO responded:
January 30, 2024
Hello, I agree that as long as your bottom fitting measures 1-1/8" deep, then the S390-36 would be the way to go. Your stamp would correspond to the 3520 strength option, which will support a sash weight between 13-18 lbs. Take a look and let us know if you have any other questions. Close up view of the S390 balance shoe.
|