|
Bob from SWISCO responded:
March 3, 2020
Thanks for writing in. This looks like either an S351-31 or S390-31. The only difference between these two balances is the 'depth' of the bottom nylon shoe, so compare both with your old hardware to see what matches best. In general, we always advise you replace the original stamp option. So for instance, for a balance stamped 30-3, this would correspond to our stamp option of 3030, which is for a window sash in the weight range of 16 through 23 lbs. If you are uncertain, weigh the window sash. Obtain that exact weight, then match it with one of the weight ranges listed alongside each stamp option. See below: Stamp Option Sash Weight Range 3010 7 to 12 lbs 3020 12 to 16 lbs 3030 16 to 23 lbs 3040 23 to 28 lbs 3050 28 to 32 lbs 3060 32 to 35 lbs |
