Royal Oak Chronograph Tourbillon 25977 OR Complete set - 44 mm 18-carat pink gold case on a black leather crocodile strap, 18-carat pink gold bezel, large black tapestry dial, luminescent indexes and hands. Display of the tourbillon at the 6 o'clock position. AP 2889 caliber movement. Crocodile leather strap with folding clasp in 18k rose gold. Hours, minutes, seconds, tourbillon and chronograph functions. Water resistant up to 50 meters / 165 feet. Tourbillon - compensates for the differences in gait caused by the adoption of different positions by a watch. The principle is to mount the balance and the exhaust in a rotating cage. The balance wheel and the escapement rotate around their common axis, passing through all the positions to average the errors. The cages or platforms of a vortex generally rotate once per minute. The ultimate in watchmaking complication. Watch in superb condition with its box, over-box and its original papers.