This is Dremel"s Aluminum Oxide 1/4" Grinding Stone Accessory Bit. FEATURES: A high-quality industrial abrasive made for extended usage. Cone-shaped stone. Ideal for sharpening, deburring, cleaning and general purpose grinding on most materials--including stainless steel. Specially designed for working with conic surfaces. Remove rust from cars and bicycles. Deburr pipes. Sharpen fishing lures. INCLUDES: One Grinding Stone Bit REQUIRES: Rotary Tool SPECS: Stone Diameter: 1/4" (6.4mm) Shank Diameter: 1/8" (3.2mm) COMMENTS: Use a Dressing Stone to clean the surface of the grinding stone and restore its original shape. kr11/14/01 ir/kh UPDATE JMM 2/5/03