The Irwin long auger wood drill bits have been designed for all general wood boring and offer a superior performance. The single spur cutting edge scribes the circumference of the hole for a smoother quality finish. The hexagon shank prevents slipping in a drill chuck or bit extension. The solid centre provides extra rigidity whilst boring, the self-feeding screw point provides faster boring in both soft and hard woods and the fully hardened body from tip to shank provides extra durability. The Irwin IRW10502742 Auger bit - long series has the following dimensions:Drillbit diameter: 8.0mm otal length: 400mm Working Length: 323mm IRWIN Wood Auger Drill Bit Long Series 8 X 400Mm in Silver