Compression Ring Hook Ring Designed for applications that require passing counterbores and retaining ring grooves. Step Ring Restricts oil flow by eliminating the straight path. Inside cut Inside surface is cut to allow the ring to be inclined during operation. So that the ring working surface lower edge line contact with the cylinder wall to assist initial running-in. Under Cut The lower edge of the working surface is cut. While being a pressure ring, it also performs as an oil control ring. Copper plated Increases initial running-in of new rings with the cylinder wall. Notch Enhances the close fit between piston ring and cylinder wall. Both –side keystone The cross section is wedge-shaped from both sides. Excellent in preventing ring sticking. Slip In Increases lubrication of oil between the ring and cylinder liner. Copper plated Increases initial running-in of new rings with the cylinder wall.