IRWIN 49915 Auger Bit Power Drill Auger Bit, Solid Center Flute, 4-1/2 in L Flute, Hex Shank, 5/16 in Dia Shank         Full length heat-treated bit with wide lands keep the bit straight as it bores through the hole. The flutes are ground behind the lands to funnel chips to the inside of the bit and away from the outside diameter. Single spur cutting edge scribes the circumference of the hole, coarse screw point provides fast boring in hard and soft woods. All bits have a 4-1/2 in twist length and a 7-1/2 in overall length.