... head of the Nail art polishing drill machine .4,Switch the speed control of the Nail art polishing ... 1,Press the Nail art polishing drill machine funtion switch on the right to HAND for manual control ... accelerate the grinding head.3,When the funtion switch of Nail art polishing drill machine is pressed ... the foot,the speed will decrease(foot switch is optional)4,The turning directions of this Nail art ...