This hot and cold compress back pack is designed for effective pain relief and muscle recovery. Made with self-absorbent polymer resin, it ships dry and instantly absorbs water, making it lightweight and easy to store. The innovative sub-box structure ensures even temperature distribution and longer-lasting cold or heat therapy. It cools quickly in the refrigerator and can also be safely heated in the microwave without leakage. Flexible and foldable, it easily wraps around the back, joints, legs, shoulders, and arms. Fully reusable and eco-friendly, it’s ideal for sports injuries, muscle fatigue, and everyday body care at home or outdoors.