Bosch Professional SelfCut Speed Spade Drill Bit Set - 13 Pieces (10-32mm)This spade bit has a 1 4 inch hex shank system and it is best for use with portable power drills. The Self Cut Speed Spade Bit performs extremely fast hole drilling. Its self feeding threaded tip enables the drill bit to effortlessly pull itself into the wood for high speed drilling with little exertion. Fast chip removal for rapid results is made possible by the specially shaped spade. In product tests, this drill bit produces holes 10 times faster