This model is in 1/700 scale. It is a combination of early test aircraft from the United States. It includes 2x Bell X-5 (One with landing gear down) and 2x Douglas D-558-1 Skystreak (One with landing gear down). The aircraft are attached as a single sprue by wires under the body of the different aircraft. Once cut the models do not require any further finishing.
According to Wikipedia: "The Bell X-5 was the first aircraft capable of changing the sweep of its wings in flight. It was inspired by the untested wartime P.1101 design of the German Messerschmitt company. In contrast with the German design which could only have its wing sweepback angle adjusted on the ground, the Bell engineers devised a system of electric motors to adjust the sweep in flight."