Remember using those heating boxes to warm our hands when we were kids? We would put the burning coal into the box, then we could either hold the hand warmer or place it in our clothes to keep us warm. But I don't know why, we can no longer see these kind of hand warming boxes. Now there is a similar product that can be used to warm our hands, a rechargeable hand warmer. This egg-shaped hand warmer is of course much more convenient to use. It doesn't require coal, but instead just needs to be charged in order to heat up. After being fully charged, it can continue to heat for 5-7 hours with a temperature between 37-43 degrees Celsius. It is very suitable for skiing, traveling, and outdoor activities.