The Sturmpanzer was a development of the Panzer IV tank designed to provide a vehicle offering direct infantry fire support, especially in urban areas. It used a Panzer IV chassis with the upper hull and turret replaced by a new casement style armored superstructure housing a new gun, the 15 centimetres (5.9 in) Sturmhaubitze (StuH) 43 L/12 developed by Skoda. It fired the same shells as the Sig 33 heavy infantry gun. Thirty-eight rounds, with separate propellant cartridges, could be carried. It used the Sfl.Zf. 1a sight. The combined weight of the shell and cartridge (38 kilograms (84 lb) for an HE shell and 8 kilograms (18 lb) for a propellant cartridge) made the work of the loader arduous, especially if the gun was elevated to a high angle.
