USAAF P-51 Aircraft Flight Operation Cards

Aircrew flight operation/cruising guide cards for the USAAF P-51D & K (North American 'Mustang') aircraft.  Information based on T.O. 01-60JE-1, July 1945.  Set of 4 plastic cards approximately 14 x 8cm. These appear to have information about the aircraft's engines pertaining to different scenarios such as the loading weight of the aircraft with external combat fuel tanks fitted etc.  They have information on RPM limits, climb data, maximum range and so on,  Probably carried on the aircraft to be used as an aide-memoire.  The cards are in excellent condition and come in the original paper envelope.  Stock code P20309.