Guide Ex Std Yz400F 98-02 80-80120C630 Valve GuideMade in the USA Made from copper based C63000 nickel aluminum bronze The 5% nickel content provides superior resistance to wear, and the approximately 80% copper content delivers outstanding heat conductivity Profiles are designed to have minimal effect on the airstream while maintaining critical cross sectional thickness in high temperature areas, which promotes high performance and endurance