Prime-Line H3578 Wood Window Sash Balance, 6-3/8 in L, Steel

This H 3578 is for a 6 lb window or 12 lb if one is used on both sides. This Wood Window Sash Balance style has been used by many manufacturers of windows for several decades. It fits a 3-1/4 in by 6-3/8 in pocket that has been mortised about 2 in above the centerline of the window frame. It is an all steel construction, with a coil spring inside that retracts aircraft cable lifters as it offsets the weight of the window (vent).