1 x IRWIN(r) Blue Groove 4X Long Flat Bit 20 x 400mm The IRWIN(r) Long Series 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 400mm in length and 10% larger in diameter for added durability. IRWIN® A08 B0073.