StuG III Ausf. E: (Sd.Kfz 142; September 1941-February 1942, 284 produced) Superstructure sides added extended rectangular armoured boxes for radio equipment. Increased space allowed room for six additional rounds of ammunition for the main gun (giving a maximum of 50) plus a machine gun. One MG 34 and seven drum-type magazines were carried in the right rear side of the fighting compartment to protect the vehicle from enemy infantry. Vehicle commanders were officially provided with SF14Z stereoscopic scissor periscopes. Stereoscopic scissor type periscopes for artillery spotters may have been used by vehicle commanders from the start.