The 3.7 cm Flak auf Fahrgestell Panzerkampfwagen IV (sf) (Sd.Kfz. 161/3), nicknamed Möbelwagen ("Moving Van") because of its boxy shape, was a self-propelled anti-aircraft gun built from the chassis of the Panzer IV tank. It was used by the Wehrmacht in the European Theatre of World War II.
In 1943, due to the waning ability of the Luftwaffe to combat enemy ground-attack aircraft, ground-based anti-aircraft weaponry was becoming increasingly important to the Wehrmacht. In early 1943, the idea of creating a gun platform on the chassis of the Panzer IV was first proposed. The prototype displayed to Hitler on December 7, 1943, used the 2 cm Flakvierling 38, which was deemed too weak for the latest aircraft, which were constantly being improved to fly higher and faster. Only a single prototype with this gun was produced before the design was rejected. A second design with an upgraded single 3.7 cm Flak 43 L/89 was approved as a temporary stopgap until better Flakpanzers could be created. 240 Möbelwagens were built, and the first production models were put into service on the Western Front in April 1944.
