The vacuum flask is a type of container that is used to store liquids or other substances to keep hot drinks hot and cold drinks cold for an extended period of time. The vacuum flask is made from a metal or plastic shell, with a rubber or plastic cup inside.

The pressure inside the flask is greater than the atmospheric pressure, which means that the liquid inside the flask cannot escape. This makes it a great choice for storing liquids that require a high level of protection from air and moisture.