On their long marches for their Roman empire legionairies carried not only their weapons with them, they also had to carry their own provisions and cooking and baking utensils.
We know that each legionary had his own supply of wheat, which was ground in a portable mill.
Our reproduction of such a mill consists of 2 halves - each of the stones is 5 cm or 1.96 inch high.
It weighs approx. 12 to 15 kg (40 lbs). The diameter of the stone is 31 cm or 12.2 inch.
It is functional, but the grain is not ground, only slightly bruised. The grains are then no longer fit for consumption, as always carried a slight abrasion of stone.