The Blue Groove Power is the world's first wood drill bit to use IRWIN's pioneering bi-metal technology, creating a drill bit with unrivalled speed and durability even in nail-embedded wood. Designed for high-speed precision drilling, it marks an end to the frustration that tradesmen experience when their drill bits strike a nail, frequently causing standard flat bits to become locked or break. The secret behind Blue Groove Power's extraordinary strength is IRWIN's bi-metal technology, a composition of two high performance components, high speed steel and carbon steel, which both have their own attributes and benefits. The high-speed steel edge provides durability and allows nail cutting, while the carbon steel body gives the bit flexibility. Each bit in the Blue Groove Power range has a self-feeding tip which helps to pull it through materials, as well as three cutting edges which enhance chip removal for a fast, clean hole. Size: 28 mm. Size: 28 mm.