The "Panzerkampfwagen IV" was developed as a 20-ton class medium support tank by Krupp-Grusion and over 12,000 units of "PzKpfw IV" were produced from October 1937 to the end of the war as a prime tank. Panzerkampfwagen IV AusfB VsKfz622 were produced using 2Serie/BW FgstNr80201 - 80242. Only 42 of Panzerkampfwagen IV AusfB were completed from April to September 1938. As with the AusfA through E were armed with a short 75cm tank gun and MG34 in the turret In the AusfB and C, a vision port and a pistol port replaced the machine gun and its ball mount in the superstructure front plate. The superstructure front plate was made from a single straight plate with the driver's visor, radio operator's visor in the same flat plane. An outer armored mantle was bolted to the turret front plate of the AusfB & C, over the internal gun mantle, covering the gaps between the internal gun mantle and the front wall of the turret In the AusfB and C cooling air intake and exhaust vents, three parallel horizontal louvers and two vertical supports were designed to retard projectiles and bullet splash entering the engine compartment.