Weld-on hubs are made of 1015-1025 steel, drilled, tapped and taper bored to receive the taper-lock bushing. They are useful for welding into fan rotors, pulleys, plate sprockets, etc., which must be firmly mounted onto shafting. Four types of hubs are available from stock. Dodge® Weld-On Hub, Taper-Lock Type S, 4-1/4 in Bore Dia, 5-1/4 in Outside Dia, 5-1/8 in Pilot Dia, 4 in Bolt Circle Dia, 2 Bolt Holes, 2 in Overall Length, Steel