Elemart(TM) USB Electric Warmer Heater Plate for Coffee Tea Beverage Mug with Light Indicator and ON/OFF Switch Portable pocket size, easy to take anywhere. Power supply by USB plug or adapter, with convenient 1m USB cable cord length for use almost anywhere. With On/Off switch control; blue LED indicates when warmer is on, the plate get hot in 10 seconds Adopt stainless steel materials in the surface heater place, its fast and safe to use and the surface easily wipes clean. Perfect for coffee, tea, hot cocoa & any other beverage need to heat.