... greater capacity, more environmentally feather, can be reusable for 500 times.Using Ceramic heating element to save energy ... Using instruction:There are three buttons, 0 for OFF, .for low temperature, .for high temperature.When the warmer is ON, ... turns green.When the switch is off, the heater and the anti-charging function do not work. ... li battery hand warmer with CE & ROHS best gift for Christmas