Ideal for making countersink holes for countersunk screw heads, as well as countersink holes for plugs. The countersinks are made of carbon steel, the surface is coated with titanium, sturdy and durable, not easy to rust, long service life. This kit is suitable for home DIY and daily use, it can drill easily and efficiently, without burrs. Universal size compatible with all types of drill bit, drilling machines, including vertical drilling machine, and other common countersink. This set of 6 90 degree 3-edged drilling cutters is suitable for working on metal and some non-metallic materials, such as carbon steel, light iron, insulation boards, PVC boards, aluminum, hardwood and soft, etc. SIZE: Head Diameter * Shank Diameter * Length 6.3MM: 6.3MM*5MM*37MM 8.3MM: 8.3MM*6MM*40MM 10.4MM:10.4MM*6MM*39MM 12.4MM:12.4MM*10MM*46MM 16.5 MM:16.5MM*10MM*47MM 20.5MM:20.5MM*10MM*47MM Package included: 1X 6pc Three chamfering drill