Adventurer's Oven

You were dubious when the merchant sold it to you, but the price was worth taking the risk.  You watched him unfold it and set it up in his store, and it certainly seemed simple enough.  That first night camping in the wild, you pulled the tin contraption from its leather bag and unfolded it.  Sure enough, putting it together to form a simple tin box was pretty easy.  The door opens easy enough, and latches tightly closed as it should.  You lay the oven on some coals created by your fire and quickly throw together a simple dough with flour and water.  Ten minutes later, freshly baked bread or buns or even biscuits are ready for eating.  The metal never seems to get hot, allowing you to move it off of the coals when you think the bread is done.  And  you always seem to know when whatever you are baking is done, as if the box is somehow telling you its time to remove the oven from the coals.  Could it be magically enchanted in some way?  There are runes along the top over the door, etched into the tin.  The fact that is bakes perfectly every single time, and weighs but a pound when its put away in its pouch, you wonder how you ever lived without it.