The Irwin Blue Groove 4X Flat Bits have a patented groove point, and cutting edge designed to cut and not scrape the timber 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. The Irwin IRW10502826 Blue Groove 4X flat bit 6 piece set includes the following pieces: 10, 13, 16, 19, 22 & 25mm