The main component of the hot pack is a high-tech polymer sealed with a high-density plastic paper. When using it, but the technology ice in the water and knead it by hand to make it expand. It is the best state to expand to about 1 cm. Take it out after the expansion is complete. Wipe off the moisture on the surface, and then heat it at a high temperature for 2 minutes. When the heat pack has no temperature, it can be directly heated for use. Features: 1. High-tech products with the best quality, the strongest durability, the highest safety and the lightest weight in the world today. 2. Has obtained ISO9002 international quality certification. Tested by an independent organization in the United States, it has the longest holding time of all ice products in the world (6 times the holding time of ordinary ice of the same size). 3. It can be reused N times, both cold and hot, 4. The lowest can be frozen to -190℃, the highest can be heated to 200℃, 5. It can be cut to any size, 6. It can be in direct contact with food and is food-grade technological ice. 7. Safe, non-toxic, environmentally friendly and energy-saving, replacing gel packs, ice bags, block ice and dry ice. For details, please contact: https://www.gel-pack.net/product/hot-pack/