The IRWIN® Blue Groove 4X Flat Bits have a patented groove point and cutting edge, designed to cut and not scrape the timber. They are 4 times faster than standard flat bits. The parabolic scoop optimises control and removal of wood chips. Increased relief angle from 12° to 17°. The shank is 152mm in length and 10% larger in diameter for added durability. This IRWIN® Blue Groove 4X Wood Flat Bit Set is supplied in a branded nylon case. Contains the following: Sizes (Ø): 6, 8, 10, 12, 13, 14, 16, 18, 19, 20, 22, 24, 25, 28, 32, 35 and 38mm.