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 casemate-style armoured 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 15 cm sIG 33 heavy infantry gun.