The US Model 1 (and subsequent Models 2 and 3), was the principle ground Anti-Aircraft Gun used by The US Military during World War II. It would remain as such until the end of The Korean War in 1953. Originally deployed in 1938, The 90mm Gun would be used by US Army National Guard and Reserve Units until 1960. While an effective Anti-Aircraft weapon. The 90mm Gun was also adapted for use as an Anti-Armor Guns as well, being mounted on various late World War II (1944) ''Tank Busters'' (Specialized Armor Tracked Vehicles). These Models would be seen in many European battles in the ''push'' for The City of Berlin (Germany) and in Italy. The M-1 Version weighed over 18,000-pounds and was mounted onto a mobile (circular) Base, capable of traversing 360-degrees with a 90 elevation. A Crew of (7) was needed. The M-1 Version used a 24-inch HE (Fragmentation) Shell, with a 63,000-foot maximum effective range.