Made by Jims machining from Aircraft quality American steel. Tappets are precision machined, heat treated and ground to less than .0002" total indicator readings at a 16 finish. The Big Axle tappets feature increased roll strength and will not deform even when used with extreme high lift cams. Available in stock (.731") and .005" oversize. Tappets are sold each and do not include the hydraulic unit, these must be ordered separately.