SODIAL(R) Rechargeable USB Powered Coffee Tea Cup Mug Warmer Automatic Stirring (Black) USB powered with built-in rechargeable Li battery, it can get recharged repeatedly. With automatic stirring function. Plug and Play, no need to install extra driver. Easy installation and easy operation. Keep your coffee, tea, or other beverage warm. Portable design, you can carry it around during travel. It's also suitable for home and office using.