Unidirectional Rotating Bezel

An elapsed time rotating bezel, often found on divers watches, that moves only in a counterclockwise direction. It is designed to prevent a diver who has unwittingly knocked the bezel off its original position from overestimating his remaining air supply. Because the bezel only moves in one direction, the diver can err only on the side of safety when timing his dive. Many are ratcheted, so that they lock into place for greater safety.