Foredom CeramCut Blue Stone, Sphere, 120 Grit 3/8 inch Dia., 1/8 inch Shank, Style A-CK8332. This tool has a ceramic and aluminum oxide abrasive grain structure superior in performance and life to standard aluminum oxides or silicon carbides. Widely used on hard metals including hardened and mild steel, steel alloys, chrome, cobalt, titanium, platinum and other ferrous metals. Also suitable for porcelain materials and wood. CeramCut Blue Stones remove material faster, run cooler and last 3-5 times longer than other abrasives. Non-impregnating and non-contaminating. 45000 RPM Max Speed. Made in USA.