Alpina Watch Seastrong Diver Heritage AL-525S4H6c. Because air supply is always limited, time spent under water is extremely precious. To ensure the hours, minutes and seconds can be easily read, and as a reminder to divers to return to the surface in good time, product designers not only provided their diving wristwatches with striking illuminated dials and hands, but also incorporated a useful rotating bezel. For safety reasons, the rotating bezel can now exclusively be turned in an anticlockwise direction. In this way the time for remaining under water as displayed by the watch can only be reduced in the event of an accidental change, never increased. Because the inventor company had placed their unilaterally positioned rotating bezel under patent protection in the 1950s, their competitors either had to be content with copies that could be displaced on both sides, or proceed in a completely new direction.