3/32" Diameter, Tungsten Carbide Cutter, 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.