In 1956, Rolex conceived of a new variant of Turn-O-Graph to honor the Thunderbirds, a U.S. Air Force squadron devoted to aerial demonstrations. Rolex built the model Reference 6609 upon Datejust (the 36mm Oyster Case), but with an 18k gold case and the rotating bezel. Rolex offered the reference of Turn-O-Graph to the Thunderbirds,