Strong 210/105L Dental Electric Micromotor Polishing Grinding Machine 65W 40000rpmStrong 210 105L Dental Electric Micromotor Polishing Grinding Machine 65W 40000rpm Rated Speed: Main power controller: 1000 45000RPM (Max) Grinder handle: 1000 40000RPM(Max) The power controller can be matched with 35K, 40K, 45K grinding machine handle. Instructions: Don't change the turning directions too frequently, otherwise, it will damage the grinding head. Turn the speed control counterclockwise to decelerate the grinding head to the minimum