The 5 cm KwK 39 L/60 (5 cm Kampfwagenkanone 39 L/60) was a German 50 mm calibre tank gun used during the Second World War, primarily as the main armament of later models of the German Panzer III tank from December 1941 onwards. It was produced when the well-armoured T-34 and KV-1 tanks were encountered in ever increasing numbers on the Eastern Front, although it was only partially successful in its role. It was later superseded by the 7.5 cm KwK 40 L/43. It was also mounted on the Sd.Kfz. 234/2 heavy armoured car, and adapted for mounting in the Me 410 aircraft.