Irwin 49905 Power Drill I-100 Auger Bit 5/16"Irwin 49905 Power Drill I-100 Auger Bit 5/16" Features:; Solid center design provides extra rigidity while boring; 7/32" Shank Size; 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, producing a faster, cleaner cut; Single-spur cutting edge scribes the circumference of the hole for a smoother finish; Coarse screw point provides fast boring in hard and soft woods; All bits have a 4-1/2" twist length and a 7-1/2" overall length; Full-length heat treated bit guards against bending in heavy-duty applications and strengthens the twist where the greatest strain occurs