Here is the link to my more-detailed review of this watch. • Casio G-Shock GW6900 I...
The G-Shock GW6900 is based on the long-running 6900 series of Casio G-Shocks. This version includes two of my favorite features. First, it has Multiband 6, which means that this is a radio controlled watch. It can receive atomic time information from any of six transmitters in different parts of the world, including WWVB which broadcasts time data from the National Institute of Standards and Technology (or NIST) in Colorado. Second, this is a "Tough Solar" watch with a solar cell built into the face of the watch. With daily exposure to everyday lighting conditions in your home or office, this watch will keep its power source charged, allowing it to run indefinitely. (Technically, the battery inside the watch will eventually wear out and won't hold a charge, but this won't happen for many, many years. Even if that happens, replacement batteries are available. By the time this watch would need a new battery you may have already beat it up pretty well anyway.)
Other great features of this watch include a world time mode, a 24-hour stopwatch, a 24-hour countdown timer, an hourly chime and five daily alarms, one of which is a "snooze" alarm which will repeat every five minutes for up to half an hour.
There are several different versions of this watch with different colors. There are many more versions which don't include the Multiband 6 or Tough Solar features (the model DW6900). Those versions may also include metal bezels in different colors and finishes (the model GM6900). Furthermore, there are a few aftermarket, third-party items our there which could allow you to change the look of this watch. Here's a video in which I used one of these conversion kits. • Casio G-Shock GW6900 M...
The GW6900 watch featured in this video uses Casio's Module 3179. Detailed instructions are available for download from Casio's website