DEWALT DCG414T1 60V MAX 1 Battery FLEXVOLT Grinder with Kickback Brake Kit Flexible - power of corded. Freedom of cordless. The world's first battery that automatically changes voltage when you change tools. Brake engages when trigger is released, stopping speeds of 1.5 seconds with standard grinding wheel Kickback brake engages when a pinch, stall, or bind-up event is sensed E-clutch activates in less than a tenth of a second when a pinch/stall is detected, shutting down the motor 9,000 RPM speed allows the use of 4-1/2" to 6" wheels