Dremel 9909 Tungsten Carbide Cutter The product is 1/8" Diameter, Tungsten Carbide Cutter 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. Do not use this cutter for drilling holes or for enlarging holes that are less than twice the diameter of the cutter. The tungsten carbide surface can easily catch the side of a hole and break the bit. For best results, insert the accessory bit all the way into the tool and then back it out slightly before tightening down. This provides plenty of shank for the collet or chuck to hold onto the bit. Secure objects to a stable surface while working.