This is the model GB-5600AB-1A, with Bluetooth v4.0 that is compatible with the iPhone 4S/5. It is housed in Casio’s classic, low-profile, square shaped case and features typical G-Shock functionality: LED backlight, world time (35 time zones with daylight savings indication), 1/100th-second stopwatch, countdown timer, up to 5 daily alarms, hourly time signal, ability to measure elapsed time, split time and 1st-2nd place times, full auto-calendar (to 2099), 12/24-hour format and more.
In addition to standard G-Shock features, it also has the new Bluetooth v4.0 functionality which when linked to an iPhone 4S/5 includes: notification of incoming calls and emails, phone finder function to enable the iPhone alarm function from the watch, warning vibration when the watch loses its connections to the iPhone, time adjustment by synchronizing with the time data received from the iPhone, built-in tilt sensor to detect movement in the watch while it is power-saving mode to automatically reconnect to the iPhone, alert function notifies users of updates from Facebook and Twitter.
Accuracy is ±15 seconds per month. Battery is good for 2 years (CR2032), assuming use of Mobile Link for 12-hours per day. Case is made of resin and measures 48.9 mm x 42.8 mm x 13.8 mm. Mineral glass protects the dial and water resistance is 200 meters.
If compared to the Seiko and Citizen GPS based watches, I believe this is more practical. Nearly everyone carries a phone. It would therefore be more effective to use the phones’ connectivity capabilities than having to design such capabilities into a watch. More of a piggy-back concept. I want one!