These mini-dehumidifiers are designed to absorb moisture out of the air from enclosed areas. Because humidity destroys guns, they're the perfect way to combat moisture in your gun safe or cabinet. Designed to be 100% reusable, they require no power or wires to operate. When your Eva-Dry's color-coded indicator shows full, simply plug the unit into a standard wall outlet. In 12-14 hours it will be completely renewed.