Features machined, smooth piston crowns for reduced carbon buildup, increased horsepower and fuel economy. Hard anodized crowns are 75% stronger than non-anodized, providing minimal expansion and reducing the chance of cold seizures when combined with Teflon/Molybdenum coated skirts. MOS2 (Teflon/Molybdenum) coated skirts perform at the highest standards, reducing friction and heat for added power and longevity. SPI rings match and interchange with the OEM design.