Self-heating food packaging is active packaging with the ability to heat food contents without external heat sources or power, usually using an exothermic chemical reaction. Packets can also be self-c
A Unitized Group Ration – Express self-heating field ration being heated in its box
Self-heating rice with quicklime and water as heating source, taken before adding water to quicklime
WW2 era Heinz/ICI self heating soup can
A flameless ration heater, colloquially an MRE heater, is a form of self-heating food packaging included in U.S. military Meal, Ready-to-Eat rations since 1993.
A pair of flameless ration heaters
A Mounted Ration Heating Device, a prototype Flameless Ration Heater. Service members would power the device using the attached cable and a running vehicle. Up to four MRE pouches could be heated at once.
The instructions advise that the heater should rest against a "rock or something"