[Chamfer Drill Bit Size] - This countersink drill bit set is machined from high-speed steels and comes in 6 different diameter sizes: 6mm (1/4'), 8mm (5/16'), 9mm (3/8'), 12mm (1/2'), 16mm (5/8'), 19mm (3/4') [Great Working] - Five-blade chamfering with a groove, easier to discharge debris and high carbon steel drill bit not easy to blunt. In addition, standard 1/4' hex shank, a variety of specifications. The automatic center punch providing a spring-loaded automatic strike when pressed against the surface, it can be adjusted, the cap regulates the striking force. [Widely Use] - Drill bits mainly used for wood openings, reaming, chamfering, screw head, etc. Also applies to MDF, plywood, acrylic, PVC board and soft metals such as aluminum, copper, etc. [Premium Design] - Ideal for driving 82 degree holes in wood and soft metals Countersunk head screws and fasteners.Suitable for DIY, home and general building/engineering. Note: Data is All manual measurement, please allow 1 - 19cm error, due to the light and display difference, there will be some color difference, depending on the physical object received.