1 quart arctic canteen
The arctic canteen is an odd looking duck that is designed for use in very cold climates. It is a double walled vacuum flask designed canteen, built with a screw in stopper for a lid that keeps the neck from freezing up. In other words, it is built exactly like a Thermos.
The same tech that keeps water from freezing in the arctic happens to do a dandy job of keeping coffee piping hot so some troops will add a 1 quart arctic canteen to their rucks and load up with hot coffee prior to stepping off on a patrol.