High Quality - The upgrade version hot water bottle is made from food grade silicone, odorless and recyclable. Wide mouth design, easy to fill up water. Knit Cover - There is a soft knit cover to prevent the hot surface from being in direct contact with your skin to cause burns. Microwave oven Available - Can be heated by microwave oven, take off the knit cover and fill in cold water, the heating time is 2-3 minutes and the heating power should be not over 1500W.