A plastic bottle with steel inside is used to keep the water cool It is useful for athletes and touristsA plastic bottle with steel inside is used to keep the water cool It is useful for athletes and tourists Wide Application: The package is convenient and firm, and not easy to slip. The product is suitable for most bottles on the market. suitable object: It can be applied to a variety of heating materials, and it can be used for water, mineral water bottles, milk boxes, etc. Intelligent constant temperature design: Precise water temperature control for