LONG LASTING HOT & COLD THEARPY: Put the ice pack in freezer for at least 1 hour for cold thearpy. Cold compress is great for sore muscles, sports injuries, chronic back pain, knee replacement surgery, etc. Heat the ice pack in a microwave for 10-20 sec or in hot water for 5-10 min for hot use. Heat compress can reduce joint stiffness, increase blood flow and relieve menstrual pain. The gel ice pack keeps the tempreture for 30-45 minutes to immensely soothe your muscles and relieve pain. DURABLE & REUSABLE: The large ice packs for injuries are filled with pliable non-toxic evenly distributed gel. Advanced Polyester edging technology makes it a durable and leak-proof nylon pack. The large cold pack is great for family use and can be used for years. SUPER FLEXIBLE & LIGHTWEIGHT: The reusable ice pack stays flexible at 0?(-18?). It is still moldable after freezed over night. The soft ice pack can wrap around your entire knee or cover your whole back. The lightweight (1380g) gel pack provides a great balance between cold and comfortable. COMFORTABLE FABRIC COVER: With washable & skin-friendly out layer, our large ice pack can effectively avoid frostbite and condensate. The soft fabric cover keeps the skin dry and comfortable, so you don’t have to look for additional dry towels while icing. EXTRA LARGE ICE PACK: The amazing 12 x 21’’ extra large ice pack is designed specially for back pain relief. Perfect for spine injuries and sciatica to calm the pain. The ice pack is also large enough for anyone to use on any body part. Very handy for any injuries.