The Rheinmetall Rh-120 is a 120 mm smoothbore tank gun designed and produced in former West Germany by the Rheinmetal-DeTec AG company, it was developed in response to Soviet advances in armour technology and development of new armoured threats. Production began in 1974, with the first version of the gun, known as the L/44 as it was 44 calibres long, used on the German Leopard 2 tank and soon produced under license for the American M1A1 Abrams and other tanks. The 120-millimetre (4.7 in) gun has a length of 5.28 metres (17.3 ft), and the gun system weighs approximately 3,317 kilograms (7,313 lb).