Insize Countersinks are made from 100% M42 Cobalt High Speed Steel. They are used for countersinking holes and deburring in a wide variety of materials including ferrous and non-ferrous metals. The triple, wide angled fluted design is self-centering allowing the user to provide a heavy, 90 degree, chamfer to the entrance of a drilled hole. This chamfer may also be required to allow the correct seating of a countersink head screw or to provide the lead in for a second machining operation such as tapping. It can be used on medium to hard materials and has the ability to be re-sharpened. Set is supplied in a quality, pressed metal storage case.