This microwave heating bottle is made of food grade silicone that is soft and durable, BPA free and FDA approval. It can withstand low temperatures of minus 20 degrees and high temperatures of 120 degrees. It is dustproof, reusable, washable. But please do not use boil water or strongly corrosive liquid to wash the bottle Heating in microwave oven: This silicone hot water bag can be heated in microwave oven with full cold water and it can be heated repeatedly. However for safe heating, please make sure to fill cold water fully and do not heat with knit. You should heat the bottle in less than 3 minutes. The microwave heating power must be less than 800W.