The HS.404 was an autocannon originally designed and produced by Hispano-Suiza. It was widely used as both an aircraft and land based weapon in the 20th century by French, British, American and numerous other military services, particularly during the Second World War. The cannon is also referred to as Birkigt type 404, after its designer Marc Birkigt, and later versions based on British development are known as 20mm Hispano. Firing a 20 mm caliber projectile, it delivered a useful load of explosive from a relatively light weapon. This made it an ideal anti-aircraft weapon for mounting on light vehicles, as well as a fighter aircraft gun, replacing the multiple 7.62 mm (.30 caliber) and .303 inch (7.7 mm) machine guns commonly used in military aircraft of the 1930s. The HS.404 was produced