Gloves can keep some of the chill away, but really cold days can chill your hands to the bone. The re-usable hand warmer uses an almost magical chemical reaction to turn it from a bag of gel into a lovely warm portable warmer that will thaw out your hands no matter how cold they are. As soon as you click the internal metal clicker, a chemical reaction spreads out from the clicker to transform the liquid into a solid material, exerting plenty of heat in the process. As a bonus to the brilliant design, it can be recharged and used again and again by simply placing it in boiling water until the inside turns back into its gel form. The liquid will hold this charge indefinitely so that you can store it away for when it is needed. You can store it in your cupboard for months, then as soon as a cold day comes along it is ready to use.