Contents: 12, 16, 18, 20, 22, 25, 28 & 32 mm. Irwin 4X Blue Groove flat bit with patented groove point and cutting edge designed to cut and not scrape the timber 4X faster. The parabolic scoop optimises control and removal of wood chips. Increased relief angle from 12° to 17°. The shank is 157 mm in length and 10% larger in diameter for added durability.