The EMX have special electronics that convert AC current to DC current encased in a plastic housing that can be positioned anywhere on a work surface. The hand dial is used to adjust and set speed. This manual style control allows you to maintain and return to a desired speed, time and again, by using the motor on/off switch rather than the speed control to [power up the unit. The EMX also has a replaceable fuse that protects the electronics during power surges and work overloads. 5" long, 5 3/4" wide, 2 5/8" high, wt. 2lbs. 2 year warranty.