Why is usually that essential? If a unidirectional bezel is knocked and accidentally moved on a dive, it could possibly only Exhibit a longer underwater time. Meaning the wearer will overestimate as opposed to underestimate immersion time, and in cases that need decompression stops, this can be a make-it-or-crack-it issue https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/