The Bofors 40 mm Automatic Gun L/60, often referred to simply as the Bofors 40 mm gun or the Bofors gun, is an anti-aircraft autocannon, designed in the 1930s by the Swedish arms manufacturer AB Bofors.  The gun was designed as an intermediate anti-aircraft gun, filling the spot between fast firing close-range small caliber anti-aircraft guns and slow firing long-range high caliber anti-aircraft guns, a role which prior was filled by older outdated guns  .  The Bofors 40 mm L/60 was perfectly suited for its time for this role and outperformed competing designs in the years leading up to World War II in both effectiveness and reliability.