2 cm Flak 30/38/Flakvierling
The Flak 30 (Flugabwehrkanone 30) and improved Flak 38 were 20 mm anti-aircraft guns used by various German forces throughout World War II. It was not only the primary German light anti-aircraft gun, but by far the most numerously produced German artillery piece throughout the war. It was produced in a variety of models, notably the Flakvierling 38 which combined four Flak 38 autocannons onto a single carriage.
Additional Information: en.wikipedia.org/wiki/2_cm_FlaK_30/38/Flakvierling