This model is in 1/700 scale. It is a combination of early test aircraft from the United States. It includes 1x Bell X-1, 1x Douglas X-3 Stiletto, 1x Northrop X-4 Bantam and 1x North American X-15. 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.The X-1 and X-15 are also available in this shop with their Motherships (Drop aircraft).
According to Wikipedia: "The research techniques used for the X-1 program became the pattern for all subsequent X-craft projects. The X-1 project assisted the postwar cooperative union between U.S. military needs, industrial capabilities, and research facilities. The flight data collected by the NACA from the X-1 tests then proved invaluable to further US fighter design throughout the latter half of the 20th century."