By using the Hex shank drill bits, you can directly drill a hole without switching chucks. The hexagonal shank (6.35mm (1/4")) allows the bit to be attached directly to a cordless impact driver drill with a single action. The solid construction contributes to rotation with a minimum runout and excellent durability. The blade edge is designed to cover both uses in percussion and rotary drilling so that you can use the bits immediately with your drill.