Kibblewhite Precision Black Diamond Exhaust Valve 40-40143 1-piece stainless steel Stellite tipped Impregnated by a special German process .002 deep and .0002 surface buildup to improve wear properties and reduce friction This process provides resistance to corrosion and wear superior to that developed by hard chromium and electrolysis nickel plating These valves are light and the profiles provide excellent flow characteristics