MaterialThe hot water bag is made of food grade silicone, that is soft and durable, long-lasting heat preservation, thick PVC liner, does not contain BPA, phthalates, and other harmful ingredients. Wide mouth design, easy to fill up water. Heating in Microwave OvenOur silicone hot pack can be heated in microwave oven. Take off the knit cover and fill in cold water, heating time is < 2 minutes, do not use light wave mode of microwave oven to heat it and the heating power should be not over 800W. Heating WaterYou can also heat water directly in the hot water bottle with cover. Allow boiling water to cool to 170F before pouring: 1.Grab the neck of hot water bottle; 2. Fill in water up to 2/3 full; 3. Exhaust excess air from the bottle; 4. Tighten on the screw cap. Cold & Hot CompressesCompared with traditional rubber hot water bags, our silicone hot water bottles are more functional, advanced thermoplastics hold the heat for up to 8 hours. It can work as an ice pack or water heating bag. Helpful AssistantThis silicone heating bag can be used as a hot water bag for pain relief, relieve menstrual cramps, stress or cramps, muscle aches, and pain in various parts of the body. Or as a cold compress for pains, sports injuries, fever and reduce swelling. Best Gift Perfect for birthday or holiday gift for girlfriend, mom, wife, family, friends.