Thermos flask. Coloured X-ray of a thermos or vacuum flask. The internal chamber (red), and the liquid that is contains, is kept hot or cold by an insulating vacuum between it and the outer walls of the flask. The internal walls of the flask may also be silvered to reflect and retain any heat that is radiated away. Most of the heat will be gained or lost through the neck of the flask.
Model release not required. Property release not required.