These diamond coated countersink burrs are mounted on a 3mm straight shank. Ideal for beveling, countersinking, carving, shaping, counterboring, chamfering and for getting into acute angled areas of glass, stone, ceramic, composites and hard woods. Ideal for V-carving, the tip is for cutting into narrow spaces, and the bottom is for cutting larger areas. You can create sharp corners and remove material with ease, and will create a smooth, professional-looking finish to drilled holes. Use with a rotary tool, flex shaft or pendant drill. Use cold water as a lubricant and coolant. Wear protective face and eye wear, and do not exceed a drill speed of 12,000 RPM, applying little to no pressure. Helpful Note: If you are looking for a very fine point, you might like to try our Diamond Cone Burrs or Point Burs.