The countersunk head is titanium coated and very strong. It has a very clean bevel with no runout and a very smooth, even bevel to make nice holes without splitting the plywood. These countersunk bits are perfect for deburring holes made with a screwdriver or to fully insert screws without protruding. Easy to use, fixed on the chuck of the electric drill, we like to work cleanly, especially to avoid accidents, because the screws that protrude can easily be injured if they are not properly inserted. This pack of 6 reinforced and very resistant knives is perfect for all jobs around the house. They hide the screws in the wood. The drill bits are made of HSS and are available in sizes: 6 mm, 8 mm, 9 mm, 12 mm, 16 mm, 19 mm, perfect for drilling wood. Product Pack of 6 Countersink Cutters with HSS 5-Flute Chamfer Hex Shank A set of 6 countersinks with different diameters that allow you to chamfer the edges of the holes. So your screw heads are well protected. These tapered knives allow you to work with wood. Easy to use, it attaches to the drill chuck. Note: Not suitable for stainless steel, cast steel, iron, copper, aluminum plating and carbon steel, thin iron plate. Material: hard steel Package included: 6x walnut knives (6mm, 8mm, 9mm , 12mm, 16mm, 19mm)