The Hot Poc (Pack of 4) reusable hand warmers from Hot Poc are designed to be enjoyed outdoors for a variety of activities like skiing, hiking and snowboarding. Their pouch is made of PVC and can be in direct contact with the skin. The liquid inside is non-toxic and composed of a saline solution. These hand warmers have a floating piece of metal inside that interacts with the liquid to trigger a thermal reaction that generates heat when you click on it. Those hand warmers are an ecological solution to stay warm during your favourite winter activities.