The 1st Royal Oak versions ended up equipped with the calibre 2121 movement, which was depending on the calibre 2120 formulated by Audemars Piguet in 1967, the world’s thinnest self-winding movement in the period with day indication, and an General height of three.05mm. The calibre 2121 was also equipped using https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/