Stainless Steel Construction: Both exhaust (XH-426) and intake (NK-842) valves are constructed from high-quality stainless steel for unparalleled durability.Chrome Stems and Hard Tips: Chrome stems and hard tips are incorporated for enhanced longevity and wear resistance.Swirl Polished and Fully Machined: The valves feature swirl polished under head areas and fully machined combustion faces to optimize movement of air and combustion efficiency.Variety of Shapes: Choose between Master (Straight Stem) and Flo shapes to suit your engine's specific requirements.Recommended for Alcohol Engines: These valves are the recommended choice for Replacement Exhaust Valves in alcohol engines, ensuring reliable performance even in demanding conditions.