Copper-based material designed specifically for use with titanium valves in high performance applications Give the seat excellent thermal characteristics as well as resistance to corrosion and wear These seats are the result of a two year KPMI R&D effort during which we recorded and verified results with 4- and 5-valve singles, multi-cylinder street bikes, and British and European 4-strokes In each test the wear, thermal conductivity and machinability surpassed the standards we set for success These seats are used by successful builders around the world in all forms of racing Made in the U.S.A.. SEAT VLV BRONZE 29MM