In the winter we can use the hand warmer when we are in the outdoor it is very ... easy to use Keep out the cold: the hand warmer In the cold season, to go to school, travel, ... 1, be sure to use the pure plant essential oils warmer oil, not use gasoline, kerosene, alcohol and other fuels ... engraved oil cap a 24-hour burn time, please, do not inject too much oil, so as to avoid wastage. hand warmer