The main Royal Oak designs were equipped with the calibre 2121 movement, which was based upon the calibre 2120 formulated by Audemars Piguet in 1967, the entire world’s thinnest self-winding motion with the period with day indication, and an Over-all peak of 3.05mm. The calibre 2121 was also Outfitted using https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/