A tachymeter scale about the bezel allows the wearer to evaluate ordinary speed more than a specific distance. Unlike other makers, Rolex engraved a much bigger scale around the bezel, which was made from chrome steel at enough time. The cal. 4040 is also chronometer Qualified by using COSC, a https://jeffreyxuojc.blogscribble.com/3564108/fascination-about-rolex-cosmograph-daytona