The carbon-fiber wing, covered in a light heat-shrunk film, has three elements: a rotating mast, the main wing, and nine adjustable rear flaps, just like those on an airplane wing. The settings are controlled by computer. "You rely much more on the instruments than on your eye," said Dutchman Dirk de Ridder, the mainsail trimmer on USA, explaining the change in technique. "The first few days were difficult for me. I would think of it like a soft sail, and it's not. You have to set the wing more to target numbers...you look at the heel angle, rudder angle, and boat speed and not at the sail itself." The wing has dozens of orange tell-tales on it, but since De Ridder could not see through it, he had fellow crewman Joey Newton check whether the flow of air was connected on the leeward side or not.