Aluminum cylinder is nickel carbide coated designed with larger water jackets Specially designed, high performance, hard anodized power valves (cannot use OEM) There is an aluminum cylinder head with a removable bronze dome allowing for a higher compression ratio and anti-detonation features (except where noted) Kit also includes a Cast-Lite flat top piston kit, and an Athena top-end gasket set that includes required seals and hardware Bolt on; no matching required except where noted. CYLINDER KIT YZ125 54MM