The first Royal Oak versions were fitted Together with the calibre 2121 motion, which was depending on the calibre 2120 made by Audemars Piguet in 1967, the earth’s thinnest self-winding motion in the period with date indicator, and an overall peak of three.05mm. The calibre 2121 was also equipped using https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/