The thermos flask is with you, whether you're driving long distances in the car, in the office or on a tough outdoor adventure. The bottle ensures that your liquid can maintain its temperature. The bottle is made with double-walled insulation with copper lining for maximum insulation. The liquid can keep the heat for 8 hours and the cold for 18 hours. The design of the bottle and the waterproof cap make it perfect to keep in your gym bag. The mug is made of non-reactive and lightweight 18/8 stainless steel, which has higher corrosion and oxidation resistance than regular steel, this prevents odor and is easy to clean. It is also BPA-free.