I've just got my hands on a packet of Meals Ready to Eat (MRE) chemical heaters. I have just tried one - they are pathetic. Followed the instructions to the letter. I might as well stuck the meal pouch under my armpit. Do these things have a shelf life? They appear to be dated US1992 NATO STOCK 8970-01-321-9153. Whats the point of them. I've now also read that these things can spontaneously catch fire when they get damp and have possibly led to the deaths of US military personnel when they were stored at an ammunition dump. They are very messy to use also.