Shapes, smooths or grinds especially hard materials including: hardened steel, stainless steel, cast iron, nonferrous metals, fired ceramics, plastics and hard woods. A high-speed cutter made of tungsten carbide, the hardest material next to diamonds. Use higher speeds for hard woods, slower speeds for metals and very slow speeds for plastics. Use the sides of the cutter (rather than the tip) for effective cutting. The only substance harder than tungsten carbide is diamond. The Dremel 9901 Tungsten Carbide Cutter is ideal for shaping, smoothing or removing material from especially hard substances, like cast iron, nonferrous metals, and hardwoods. The tungsten carbide cutter can be used in virtually any Dremel rotary tool.