Product Description Specifications Documentation P8H Heavy Duty Hex Shaft, 5/8in across flats x 3/4in long made from 4142 Hardened Alloy with a 1/4-20 end tap.This shaft will only work in a P8H Heavy Duty gearbox with a P8H Heavy Duty Front Block. Hex: 1/2 in Length (From Face): 3/4 in Keyway: 3/16 in End Tap: 1/4-20 Material: 4142 Hardened Alloy Click arrow in center of image to load and interact with it Your browser does not support iframes.