Using this G-Shock watch is a breeze. To use the world time feature, just press the relevant button on the side of the watch to switch between different time zones. The stopwatch can be started, stopped, and reset using the buttons on the case. The high - brightness LED light can be turned on by pressing the large front button. When it comes to water resistance, it can handle being submerged up to 200 meters, but it's best not to press the buttons underwater. For maintenance, wipe the watch with a soft, dry cloth regularly to keep it clean. Avoid exposing it to extreme temperatures or strong magnetic fields. When the 10 - year battery runs out, have it replaced by a professional to ensure proper functioning.