Material: SUH3(4CrSi2Mo) / SUH35(5Cr21Mn9Ni4N) Surface Welding: we adopt welding wear-resistant alloy on sealing section and small end Jumpiness of Sealing Surface: ≤0.03mm Valve Stem Surface Roughness: ≤Ra0.4 Micrometer Valve Stem Diameter Tolerance: -0.035 0.050mm Valve Stem Circularity: ≤0.002mm Valve Cotter Position: -0 0.05mm Small End Hardness: HRC50 60