The Fisura Thermo and Donut Hand Warmer (2 units) is the ideal set of pocket-sized thermal bags to provide immediate warmth to your hands on the coldest winter days. Made of durable plastic and filled with a sodium acetate and water solution, these reusable hand warmers are easily activated by pressing the internal metal disc, causing a crystallization reaction that instantly generates a comfortable temperature. After use, simply boil them wrapped in a cloth in hot water for about 5 minutes so that the crystals return to a liquid state, ready for a new use. With their fun thermos and donut shapes, they are perfect to carry in your jacket pockets during outdoor walks, commutes to work, or ski trips.