good day dear ms.Grace Liu. i am interested in your fue device. but i am never used like that. it is interesting how long it can work with battarey and what is the rpm>would not you send me any video about it?because as we know the motor must work silent and vibration free..if we can be sure that it is vibration free and on inserting into the skin it will not stop working,we would order it regards dr.rafcik Show More