The initial Royal Oak styles were fitted With all the calibre 2121 movement, which was dependant on the calibre 2120 formulated by Audemars Piguet in 1967, the world’s thinnest self-winding motion in the era with day sign, and an General peak of three.05mm. The calibre 2121 was also equipped by https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/