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Are these hot packs suitable for use with any kind of meal?
The flame-less heaters are designed for use with MRE ready to eat meals.
However successful experiments shows you can heat the contents of tins
in flame-less heater pouch. But you will need to move the tin around inside the heater, but be aware the activation water in the heater gets hot, so care must be taken when handling the hot water.
You can also add cold water to a freeze dried meal, and heat the meal, but is is very important that you do not allow the water from the heating pouch to be mixed with the food