The heater is a simple combination of powdered food grade iron and magnesium, salt, and water. When water is poured onto the included heater pad, the heater releases enough heat to warm-up the pre-cooked meal to 100+ degrees Fahrenheit in approximately 12 minutes. … It make for a mess because I eat them at my desk at work. When the bag starts …
https://www.amazon.com/MRE-Flameless-Heater-Pack-12/dp/B00KI3MC6O