Bob from SWISCO responded:
May 13, 2019
Hi Jack. Your pivot shoe looks like our 15-180. This is compatible with our Series 190 Coil Balances. I'd confirm the exact weight of the sash to be safe, but if it weighs 10 lbs, you could use one of our S190-540 5 lb coil springs on each side of your sash, to equal 10 lbs of support. |