Why is the fact vital? If a unidirectional bezel is knocked and accidentally moved on the dive, it may only Show a longer underwater time. Which means the wearer will overestimate rather then underestimate immersion time, and in cases that require decompression stops, This may be a make-it-or-break-it component that https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/