[ZINC ALLOY MATERIAL] This hand warmer is made of high quality zinc alloy material, and the is mirror polished, smooth and textured, durable and long lasting. [HOLLOW DESIGN] The special heating catalyst generates heat and dissipates it from the holes to achieve a heating effect, good thermal conductivity, and continuous constant temperature. [FUEL CAN] The catalyst hand warmer is equipped with a leakproof fuel can. Insert the fuel can into the oil filling port. It is easy to refuel without leakage, and it is convenient and quick to use (no oil). [MINI SIZE] Light weight, small size, compact, light, can be put in a pocket, carry it with you, suitable for home, office, outdoor, travel, camping, picnic and other occasion. [NO ELECTRICITY] This hand warmer does not need electricity, no open , no smoke, constant temperature and warmth, safe and comfortable, suitable for winter use.