Product Description Professionals can now improve their productivity and accuracy with IRWIN��s innovative range. The 18x152mm Blue Groove 4X wood boring bit raises the bar on tool quality and performance. The cutting edge technology incorporates true �cutting edges� that glide through the wood versus scraping its way through. The latest generation Blue Groove Power is adding extreme durability thanks to Bi-Metal Technology. Double cutting spurs scribe outside of the hole, reducing breakout. Thicker cutting edge for longer drilling life. Blue Groove point & cutting edge for faster chip removal. 10% Larger shank for added durability. Hex shank prevent bit slipping in chuck.