Channel Balance Identification

Thanks for posting. See our S380-37 Channel Balance. Just compare the dimensions, especially the depth of the bottom nylon attachment (1")--if this is different let us know. Your stamp option of 3650 corresponds to a window sash weight range of 30 through 35 lbs.If you are uncertain this is correct, you can always weigh your window sash to make sure it fits within this weight range. Let us know if you have any questions.