Makita HR4000C 1-9/16-Inch Rotary Hammer SDS-Max, Variable Speed Reduced vibration for less operator fatigue Electronic variable speed control dial (230 - 450 RPM) for easier hole starts LED light indicates when to replace carbon brushes, and if there's a problem with the switch or power source Ball clutch torque limiter ensures stable torque control One-touch sliding chuck for easy bit installation and removal