NR Series 21100 reduction gearbox 1 inch shaft 2:1 gear reduction 16 hpNR Series bolt on reduction gearbox 2: 1 gear reduction For 1 inch shaft engines Keyway 1 4 inch Rated up to 16 hp Designed to fit most medium frame (1 inch bore) 4 cycle engines Convenient bolt on design adapts to most engine makes and models Provides flexibility in engine selection by eliminating the need to purchase costly special engines with lengthy delivery lead times Constructed of rugged, aluminum castings and precision machined gears for