Foredom Typhoon Sphere, Fine (blue) Grit, 7/16 inch Dia., 1/8 inch Shank, Style A-KB18339. Typhoons have unique structurally aligned points that leave a smoother finish than other types of tungsten carbide burs. Ideal for rapid and aggressive shaping and roughing out work on hard and soft wood, acrylic, die, stone, plaster, hard rubber and fiberglass. Typhoon burs last longer and do not load as quickly. Coarse (red) grit is more aggressive than fine (blue) grit but both will remove a lot of material quickly. 35000 RPM Max Speed. Made in USA. Clean with a Brass Brush. Do not use a file card or steel brush to clean Typhoon burs and sleeves.