The Casio G-Shock Classic GW-7900B-1ER is a men's watch that works on light energy. You read the time, 24 hour indication and date on it. You also use the watch as a stopwatch or alarm and also look at the moon phases and the tides. Thanks to the automatic calibration, the position of the hands is checked and corrected every hour. So you always know exactly what time it is, even if the hands are staggered by magnetism or shock. Thanks to the watch is 20 bar waterproof, so you wear it while swimming.