Bosch 11232EVS 1-1/2-Inch Variable Speed Spline Rotary Hammer Electro-pneumatic impact system - Piston Hits air column to minimize vibration, yet deliver maximum impact force Constant-ResponseTM Circuitry - Provides soft-start and constantly monitors and adjust power to maintain desired RPM and impact force for consistent performance and control Single-function control - Hammer with rotation only Variable-speed dial - For accurate bit starting Integral clutch - Helps minimize recoil in high-torque situations