Frequently used in today's OEM factory engines and mild to moderately aggressive performance engines, hydraulic roller cams use lifters equipped with a roller wheel that tracks along the camshaft lobe, reducing wear and friction, and enabling faster lobe ramp rates than flat tappet cams. These quiet operation lifters feature the same internal design as hydraulic flat tappet lifters with internal cavities and pistons but do not rotate within the lifter bore. Suited for typical street or moderate race engine speeds, the lifters are pre-loaded and do not require a lash setting. Most OEM hydraulic roller camshafts are limited to 6200 rpm and performance aftermarket systems to approximately 6800 rpm. Hydraulic roller lifters require an appropriately selected valve spring to maintain control and avoid lifter float at higher engine rpm. Hydraulic roller lifters can be re-used with multiple camshafts, however they are more costly than any form of flat tappet lifters.