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 IRW10502818 Blue Groove 4x flat bit has the following specific dimension:
Diameter: 28mm