Features: brand new and high quality Wood plug cutter drill bit must be used on a drill press instead of a hand held drill, the cuts then will be precise and clean. For the hand electric drill and for bench drill, recommend for bench drill, centering easily. The rotating speed should not be too fast, otherwise it is easy to produce smoke, blackening and so on. The wood plug cutters are made of high quality metal. The cutter set achieves excellent finish when using same timber. The curve at the top is good for chip removal and the perforation is more efficient. Diameter sizes include 1/4";3/8";1/2";5/8" (6mm/10mm/13mm/16mm) Specifications: Material:Metal Claw Type/ Barrel Type Size:as the Picture Show Package Includes: 4 Pieces Wood Plug Cutter Drill Bit /Set note: Please allow 0-3mm errors due to manual measurement. Item color displayed in photos may be showing slightly different on your computer monitor since monitors are not calibrated same.