Using this G-Shock is easy. To access the world time and stopwatch features, just use the buttons on the watch. To turn on the high - brightness LED light, press the large button on the front of the case. When it comes to maintenance, since it has 200 - meter water resistance, you can wear it while swimming or doing water - related activities, but don't open the case underwater. As for the battery, it lasts about 10 years on a CR2025, so you don't need to replace it often. Keep it away from strong magnetic fields and extreme temperatures to ensure its normal operation. If you have any problems, it's best to take it to a professional watch repairer.