This model is in 1/700 scale. It is designed as a single sprue connected by wires under the aircraft's engines. Once cut the models do not require any work to finish. In this kit one aircraft is in 'take-off / thrusters down" mode and one is in normal taxi mode.
According to Wikipedia: The Dornier Do 31 was a West German experimental VTOL jet transport built by Dornier. The Do 31 was designed to meet a NATO specification (BMR-4) for a tactical support aircraft for the EWR VJ 101 VTOL strike aircraft designed under the NATO contract of BMR-3. The project was cancelled in 1970 due to high costs, technical problems and a change of requirement.