The Stridsvagn 103 (Strv 103), also known as the S-Tank, was a Swedish post-war main battle tank. It was known for its unconventional turretless design, with a fixed gun traversed by engaging the tracks and elevated by adjusting the hull suspension. Turretless armored fighting vehicles are usually classified as assault guns or tank destroyers, but the Strv 103 is considered a main battle tank because of its gun laying ability and its designated combat role matches those of other tanks. It is the only main battle tank and the only tank of any kind since the World War II era to dispense with a turret. The Strv 103 was designed and manufactured in Sweden. It was developed in the 1950's and was the first main battle tank to use a turbine engine. The result was a very low-profile design with an emphasis on defense and heightened crew protection level. The Strv 103 formed a major portion of the Swedish armored forces from the 1960's to part of the 1990's, but have since been removed from service in favor of the Stridsvagn 122, a Swedish variant of the German Leopard 2 main battle tank.