For a fully cooked meal, warm is fine, but if you want to cook rice, pasta, or reconstitute freeze dried vegetables and other popular survival foods, you really need some heat, and you need that heat over at least 15-20 minutes. Until now I had yet to find a chemical heater that would deliver this kind of performance, this is the Flameless Ration heater from selfheatingbag.com.
The Mealspec Ration heater works very simply. You open the out plastic bag, take out the chemical heater pack, drop that back into the bag, then add a little bit of water and whatever you want to cook. Within seconds of pouring the water into the Mealspec Ration Heater, it boils, then it continues to boil, we found, for at least 20 minutes. You wouldn’t think that little packet could provide that much gumption, but it does. The Flameless Ration heater easily cooked the rice to done, and the meal was just as good as if it had been cooked on a stove. This is an AMAZING survival product, and for a couple bucks each, you should buy a bunch of them.