Review (5/5): Actually works!
This came already charged. No batteries, is a usb charging device. I had bad black tartar on the backs of my front teeth, and this little tool got it all off. I was skeptical about how well a home tool would work, but I am pleasantly surprised. It was also gentle with my gums. I would recommend this product as a great tool for in between dental visits, but not in place of them.