This set includes 8 of the most popular shapes in a fitted case. With a 1/4-inch shank, it is suitable for processing various metals and most rotary grinders. Excellent choice for precise metal removal when shaping, leveling, or porting cast iron, steel, and other ferrous metals. of raw virgin tungsten carbide burrs that have a very long service life, 10 times the durability of other HSS burrs and 200 times the durability of small wheels. The hardness can reach HRC70, sharp and sturdy. PRECISE DOUBLE CUT: Double cut style, right and left helical flutes combine to produce a chisel-like cutting tooth, this precision, when combined with precision grinders, results in smooth operation, fast metal removal and fine finishes. WIDELY APPLICATION: Widely used for metalworking, tool making, model engineering, wood carving, jewelry making, welding, chamfering, casting, deburring, grinding, cylinder head porting and sculpting. Include body shops, fabrication shops, brake shops, industrial shops, die makers. SIZE INFORMATION Shank Dia: 6mm (1/4 inch) Fits for most rotary tools with 1/4" chuck, large size head can do better carving and grinding jobs. MATERIAL Made of heat-treated tungsten carbide material, sharp and wear-resistant, can bring high efficiency grinding and carving experiences. VARIOUS SHAPE This kit includes 8 different shapes of head, 1pc for each shape with double cut, can meet your different requirements. ON WOOD Double-cut file, suit for wood, aluminum and other soft metal material. Mainly be used with electric or air tools. ON PURE COPPER Can be used for metal or nonmetal carving, mold cavity processing, impeller passage grinding and so on. ON ALUMINUM Suggest rotating speed is between 6000-50000rpm. The cutting file should be placed in a correct place and suggest to wear safety goggles while operating.