An external bezel on a dive watch that only turns in one direction (counter-clockwise), ensuring that it isn’t accidentally rotated the other way for safety.
A globally recognized standard for time coordinated to earth’s rotational speed. While it seems similar to Greenwich Mean Time, the UTC standard is not linked to the 24 timezones like GMT. The notation is in 24 hour format, in digits only (i.e. 1300, 1400, etc). Time changes in one hour increments each time a longitude is crossed when travelling (+1 heading West, -1 heading East). The UTC timezones are considered invariable as based on the International Atomic Time, calculated by a network of 350 atomic clocks around the world. In watchmaking terms both GMT and UTC displays offer the same practicality; a second timezone.
