The initial Royal Oak versions have been equipped with the calibre 2121 motion, which was dependant on the calibre 2120 formulated by Audemars Piguet in 1967, the earth’s thinnest self-winding movement of your era with day indicator, and an overall top of 3.05mm. The calibre 2121 was also Outfitted using https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/