They look interesting and ideal for both general and fall back purposes. Do they have any special storage requirements?
We had something similar in the fire service for feeding the troops at large or protracted incidents, although in that case the food was in self heating cans.
View attachment 77241
Just use the pricker (supplied) to pierce the area surrounding the lid in several places and a short while later after an exothermic reaction has taken place, you had yourself a hot meal in a tin. You had to remember to open the tin slightly or the owner could end up wearing most of it. I used to carry a couple in my car. They were ideal for those occasions where I found myself tired and cold, kicking my heals somewhere in the middle of the night. One of those chaps made all the difference.