Review (1/5): Very poor functionality.  Don't waste your money!
The little motor inside this is EXTREMELY WEAK, using brand-new, high-quality AA batteries. It stops turning at the application of the slightest pressure, and NO, that ain't no safety feature. It's just cheap and powerless. Changing batteries and putting on the second head is absolutely no help. It is slower than an emery board. A POS. I threw it out, after repeatedly trying it for a month. (One contributor mistakenly wrote that "it uses AAA batteries"....not so.)