SD:FlaK 39(f)

 is a German Anti-air unit added in Back to Hell.

Overview
FlaK 39(f) was the German designation for the Hotchkiss 25 mm anti-aircraft gun. The French military after World War I expressed a need for  anti-aircraft autocannon. Hotchkiss 25 mm anti-aircraft gun was submitted but not accepted for French use so the design was exported. With the international situation was worsening in 1938 France decided to reconsider its refusal to Hotchkiss since the winning design from  Schneider  was not ready for service. The export guns for originally for Romania was taken into service. The original tripod was replaced with triangular base with a two-wheel carriage. These improved version was planned to be put into mass production but the Battle of France only limited guns were in service hampering the French Army Air Defense.

These guns were used in various ways ranging from coastal defense flak batteries to Flak Batteries of the Flak-Brigade 1.