Makita XAG06MB 18V LXT BL Grinder Kit, 4-1/2" Automatic Speed Change technology adjusts speed and torque during operation for optimum performance Efficient BL Brushless motor is electronically controlled to optimize battery energy use for up to 50% longer run time per charge The electronically-controlled BL Brushless Motor efficiently uses energy to match torque and RPM to the changing demands of the application Compact and ergonomic design at only 14-1/4" long Weighs only 5.6 lbs. with battery for reduced operator fatigue