The Grumman FM-2 Wildcat was a carrier and land-based fighter used by the U.S. Navy and U.S. Marine Corps during World War II. Known for its ruggedness, ability to take enemy fire, and return safely, the FM-2 Wildcat was a formidable opponent against more maneuverable aircraft such as the Japanese A6M Zero. The FM-2 Wildcat was a General Motors produced version of the F4F Wildcat primarily used in the Atlantic to escort allied supply convoys. Notable improvements to the FM-2 Wildcat included an upgraded vertical stabilizer, a more powerful engine, and increased ammunition capacity. With four .50 caliber machine guns and a 1,350 horsepower R-1820-65 engine, the FM-2 Wildcat and Wildcat variants achieved a 7-1 kill ratio by the end of World War II.