Warbirdsim reports on their site “…… One year after initial conception, the highly anticipated first release of Warbirdsim’s North American Mustang Series is ready to take to the skies – primed and waiting for everyone to experience & fly. There are FOUR packages. Each available as download or box. Fighter Pairs downloads or boxes include two aircraft in two paint schemes. Choose from the P-51B, P-51C or Mustang III variants. Each of the Fighter Pairs Boxes also includes a printed, panel guide….”. More info here.