This kept my food warm after 8 hours outside in arctic double negative degrees. I would say this is for your food, what the double sealed vacuum water/tea/coffee thermoses they use in Swedish(maybe finnish?) Ranger/Jägare/(Jäkkari)? units, and in swedish prisons for some odd reason. Indoors boiling water added would still scald your lips if drunk after 24 hours, in freezing arctic temperatures, it will still be quite warm or even scalding after 18 hours. Would love if varusteleka got the military ones that show the outside temperature aswell. Very happy with my food thermos,volume is VERY generous and can easily feed two large adults depending on what youre eating ofc. Obviously in freezing conditions, keep close to body in pack with other things around it to have a warmer ambient temperature and avoid wind chill which can be twice as cold as the freezing ambient temperature outside.