I have seen them and pondered trying them but I declined. I don't believe you can release that amount of heat without some kind of radiation or chemical reaction. I think I will stick to my Stouffer dinners and hot box.. When I get my new truck I am going to put in a microwave (radiation) and buy me some Hungryman dinners. I know my body must be immune to that type of radiation by now. Thank god for nutritional supplements to replace what little we did have before we nuked them.
The way our technology is growing, soon we will be able to cook dinner ourselves right in our rigs.