MAHLE Original plasma-moly ductile ring sets are designed for the serious racer. These sets feature rings that maximize combustion sealing and minimize frictional losses to increase horsepower and oil control. These sets include reduced radial wall (RRW) top rings, and CP-20T oil rings to reduce tension, improve conformability and maximize power output. Ring sets with low and ultra low tension oil rings are not recommended for street use and should utilize a vacuum pump for maximum performance.