Bosch RH540S 1-9/16-Inch Spline Combination Rotary Hammer Spline Bit System: Accommodates all accessories with spline or 3/4-Inch round hex shanks Best in class Impact Energy: Impact energy of 6.1 ft. lbs provides maximum productivity in all day drilling and chiseling applications Combination Dual Mode Selector Knob: Select between hammer drilling, chiseling only and the Varo-Lock function Varo-Lock Positioning: Rotates and locks chisel into 12 different positions to optimize working angle Variable Speed Dial: For controlled drilling and chiseling applications