Yes, they look like standard, oval-shaped water canteens as used by the Wehrmacht in WW2. I am not sure how precisely they are attached to the turret - but these items of kit often came with short leather straps that could be used to attach them to a belt, for example. Some of these canteens seem to have cords or straps at the neck connecting them to the turret, but I cannot make out how they are fixed to it. Useful in the desert, in any case. There is quite a bit of gear stowed on the back of this Pz III, one way or another. The Pz III seems to have had good functionality in a secondary role as equipment carrier. Best regards, JR.