The DeWalt D21570K diamond core hammer drill motor which provides improved performance in applications with diamond dry core bits up to 127mm in bricks or soft masonry. Features and Benefits: Electronics provide e-clutch, power-up and overload protection Two speed gearbox for increased versatility when drilling in wood, metal and concrete with standard drill bits Electro-Mechanical clutch increases user control and protection Heavy duty 16mm steel chuck offering excellent durability and bit retention Innovative mode selection collar allows intuitive control for optimal performance