Why is always that crucial? If a unidirectional bezel is knocked and unintentionally moved on the dive, it could only Show a longer underwater time. That means the wearer will overestimate as opposed to underestimate immersion time, and in circumstances that need decompression stops, This may be a make-it-or-crack-it issue https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/