This is a Series 210 replacement constant force balance system for tilt windows. It moderates the operation of your window sash using a specifically calibrated coil springs that allows the window to stay open when raised and remain shut when closed.
This balance comes complete with a pivot shoe, three coil springs, and coil spring covers.
The springs are stainless steel and coated for low friction and corrosion resistance.
Travel extension: 37-1/2"
Fits pocket size 7/8" x 1-1/4" (.880 x 1.292).
A pair of 30 lb assemblies will carry 57 to 60.99 lbs, (sold individually). The weight you need should be indicated as a stamp or imprint on your old balance cartridge cover.