Casio G-Shock GM-2100 Series - GM-2100-1AER

Setting procedures vary slightly by module, but typically you'll use the 'Adjust' button (often top-left) to enter setting mode, then 'Mode' to cycle through settings (hour, minute, date, etc.). The analog hands can usually be synchronized with the digital time automatically or manually. Refer to the detailed instruction manual for your specific module number, which can be found online by searching for 'Casio [Module Number] manual'.

With a 200m (20 ATM) water resistance rating, the watch is suitable for recreational diving (scuba diving) as well as swimming and snorkeling. However, it is not an ISO-certified dive watch for saturation diving. Always ensure buttons are not operated underwater.

The watch uses a standard button-cell battery. Specific battery life can vary based on usage of features like illumination and alarms, but G-Shock batteries typically last for several years. The exact battery type will be specified in the watch's module manual. It's recommended to have battery replacements done by a professional to ensure water resistance is maintained.

While the strap is replaceable, G-Shock straps are often specifically designed for their respective models, especially considering the integration with the case. Aftermarket straps may be available, but ensure they are compatible with the GM-2100 series to maintain proper fit and function. Professional installation might be advisable.

The World Time function allows you to view the current time in different cities or time zones around the world. You can typically select from a list of pre-programmed city codes, making it convenient for travelers or those communicating across time zones.

The Casio G-Shock GM-2100-1AER comes with a 2-year manufacturer's warranty. This covers manufacturing defects but generally excludes damage from misuse, accidents, or normal wear and tear.

This often indicates a low battery. Replace the battery with a new one. If the issue persists, contact customer support or a certified watch repair shop. Ensure the illumination function is not constantly activated, draining the battery.

First, manually adjust both the digital and analog times to synchronize them according to the user manual. Note that the watch has an accuracy of +/- 15 seconds per month, which is normal for a quartz movement. If inaccuracy is significantly worse, a battery replacement or professional service may be required.

This suggests a potential compromise in the watch's water resistance. Stop using the watch in water immediately and take it to an authorized service center for inspection and repair. Do not attempt to dry it yourself, as this can cause further damage.

Rinse the watch under fresh running water to clear any accumulated dirt or grime around the buttons. If the buttons remain stiff, avoid forcing them and seek professional service, as internal mechanisms might be affected.