Tungsten Carbide Cutter, 1/8" Diameter With 1/8" Shank, Carbide Is The Next Hardest Material To Diamonds, Used For Shaping, Smoothing & Material Removal, Use On Hardened Steel, Stainless Steel, Cast Iron, Non Ferrous Metals, Fired Ceramics, Plastics, Hardwoods & Other Hard Materials, Do Not Run In Excess Of 35,000 RPM.