Why is that critical? If a unidirectional bezel is knocked and unintentionally moved on the dive, it might only Show an extended underwater time. Meaning the wearer will overestimate instead of underestimate immersion time, and in circumstances that call for decompression stops, This may be a make-it-or-crack-it issue that helps https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/