The German ministry of War demanded for a mid size calibre anti aircraft gun closing the gap between the calibres 3.7 cm and 8.8 cm. Besides the 5cm Flak 41 which has been introduced in November
1941 Rheinmetall-Borsig as well as Krupp started with the development of an automated weapon with the calibre 5,5cm in 1942. Although Krupp could present a smarter design which was 300 kg lighter
than the prototype of the competitor, their testing results were not convincing. Consequently Rheinmetall improved their gun and finalized the weapon as version two (VG2 = Versuchsgeschütz
2) in 1943. The final version has been produced in February 1945 but there is no evidence that the gun ever saw action.
The existing trailer Sd.Ah. 204 was intended to move the gun which was mounted on a base with three hydraulic supports.