The Audemars Piguet Royal Oak 77321 has a case of 33mm, which houses the self-winding caliber 2240. Reference 77321BA.ZZ.D012CR.01 has a yellow gold case and a mother-of-pearl dial.
Basic thickness : 4.00 mm Total diameter : 21.30 mm Frequency : 28,800 vibrations/hour (4 Hz) Number of jewels : 28 Minimal power reserve : approx. 40 hours Unidirectional automatic winding (clockwise – the dial side) Oscillating weight mounted on an unlubricated ceramic ball bearing, with one segment of the weight made of 21-carat gold Balance with variable inertia blocks Flat balance-spring Mobile stud-holder
