A thermos flask is a container that keeps things hot or cold for a time. It has an insulation that keeps the temperature the same which is really good for carrying tea or coffee or water when you are traveling or at the office or school or outside. The thermos flask is strong. Does not leak so it helps keep your drinks fresh and, at the right temperature all day long. You can use a thermos flask for lots of things like carrying tea or coffee or water. It will stay hot or cold for a long time.