Yet a bucket tappet contains extra weight—the length necessary to guide it in its bore, and its extra width, projecting beyond the narrow cam lobe on both sides. When it becomes necessary to make valve-train parts as light as possible to allow operation at high engine rpm and/or high valve acceleration rates, the finger-type cam follower is the best choice. It is a lever, pivoted at one end with the other end bearing against the end of the valve stem, and it is in no part wider than the cam lobe. Facing the cam lobe is a smoothly ground curved pad, given great surface hardness to resist wear. As the cam lobe presses against this pad, the moving end of the lever pushes against the valve stem, opening the valve. As always, continuous lubrication is the key to durability.