The Flak 38 (German: Flugabwehrkanone 30; English: )Anti-aircraft gun 38) was a German anti-aircraft gun designed in the late 1930s by Rheinmetall. It was an improved version of the FlaK 30 (itself based off the Swiss Solothurn ST-5), with a vast increase in its rate of fire from 120 RPM to 220 RPM. It fired 20mmx138mm B rounds and was the primary German anti-aircraft gun used during World War II.
In Battlefield 1942, the Flak 38 is the Axis forces' anti-aircraft gun, issued to the Wehrmacht, Afrika Korps and Imperial Japanese Navy, as well as to the Royal Italian Army in The Road to Rome and to the Waffen-SS in Secret Weapons of WWII.
As its role suggests, it is intended to be used against enemy aircraft as is quite effective at taking down targets at close to medium range. It has generally bad accuracy, though its rounds explode one they're near a target and still deal damage. At close range, the shots fire slightly to the left of the weapon's aim point.
The Flak 38 can also damage ground vehicles, even tanks, and to a relatively effective extent, though the main problem is to have an angle at which the Flak 38 can hit these vehicles, as it cannot aim under a 0° angle.
It is the equivalent of the Allies' 40mm Bofors.