Why is important? If a unidirectional bezel is knocked and accidentally moved on a dive, it could only Exhibit a longer underwater time. That means the wearer will overestimate rather then underestimate immersion time, and in conditions that need decompression stops, this can be a make-it-or-break-it variable that assists avert https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/