According to Wikipedia, The Flak 30 (Flugzeugabwehrkanone 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.[1] It was produced in a variety of models, notably the Flakvierling 38 which combined four Flak 38 autocannons onto a single carriage.    Meanwhile, Navweaps.com says that The later C/38 was a much improved weapon which used a 40 round magazine. A very successful variation of this weapon was the Flak 35, which combined four C/38 guns in a single quad mounting. A three-dimensional stabilized naval-mount was introduced in 1944.   The C/38 was also produced in very sophisticated twin mount for U-boats. These were able to withstand a 550 foot (200 m) diving depth.

There are four 2cm FLAK C38 weapons in the packages.   One raft contains the two part mount and shields, the other the four 2cm quad barrel assemblies.   The parts have thin, curved lower shields, seats with separate backs, elevation and traverse wheels, very thin barrels, ammunition clips and what appear to be gun sights on the upper shield.   Some of these parts are incredibly thin. 

This is Black Cat Models set AC350066b, 2cm FLAK C 38 vierling mount U-boat version with shield (x4). They retail for about $8.25 USD, and are available directly from Black Cat Models - who I'd like to thank for this review sample - or from some of our other fine sponsors.   Highly recommended.