Proxxon tungsten carbide burrs, flame shaped burr, 5/16-Inch by 1/2-Inch. Great for carving and sculpting. For use on wood, rubber, plastics, foam, fiberglass and silicone. Will cut with or against the grain. Burrs can easily be cleaned by brushing or burning of without damaging the needle like teeth. Rpm: 5,000-20,000. Do not use on metal.Will cut against grainEasily cleaned by brushing or burning off without damaging the needle like teeth