LED Display Box installed R.P.M is shown in LED display box for easy work. Various R.P.M control method R.P.M can be controlled by Hand or Foot/Knee using Hand, Foot/Knee switch. R.P.M control function for safety R.P.M can be selected min 0~max 60,000 performance. Can be controlled R.P.M by Foot or Knee within the selected range of R.P.M by dial. It optimizes for safety and operation efficiency. LED display is show the stood R.P.M. It is convenient to operate again in same R.P.M. AUTO CRUSE function Keep the selected speed and direction, need not push the Foot/Knee. Useful to work a constant speed. Self Diagnosis & Reset function It diagnoses by itself and shows Error Code (E1, E2, E3) in LED box when it is breakdown and malfunction and turn on the Power Switch for reset after the problem solutions.