Lunati Hydraulic Roller Tappet Camshafts combine the best of mechanical roller and hydraulic flat tappet designs. They allow an aggresive, more powerful profile, such as higher lift and more area under the curve without the added duration needed to "ramp up" a flat tappet. Other benefits of hydraulic roller over flat tappet lifters: quiet operation, simple valve lash setting, lower frictional force, less wear, and rollers do not need replaced when changing camshafts.