During the original planning for mechanized infantry formations, the equipment was to consist of the Stug as the Assault vehicle while the infantry were to be carried in semi-tracked vehicles. To standardize on this set up, it was decided to design ammunition carrier and observation vehicles for Assault Gun Formations on the chassis of one of the semi-tracked vehicles. This resulted in the Sd.Kfz.252 and 253 vehicles. Both vehicles had a fully enclosed fighting compartment with access through roof hatches and rear door.