Upgrade the retro look you love with the octagonal GA-2100 line, which inherits the design concept of the very first G-SHOCK, but now with Smartphone Link and Tough Solar power.

Basic Information
Case size (L× W× H)
48.5 × 45.4 × 11.9 mm
Weight
52 g
Case and bezel material
Carbon / Resin　
Band
Resin Band
Construction
Shock Resistant
Carbon Core Guard structure
Water resistance
200-meter water resistance
Time adjustment
Bluetooth: Connects to a smartphone and automatically adjusts the time
Power supply and battery life
Tough Solar (Solar powered)
Smartphone Link/App Connectivity Features
Smartphone Link feature
Mobile link (Wireless linking using Bluetooth®)
Apps
CASIO WATCHES
App connectivity feature
Auto time adjustment
Easy watch setting
Approximately 300 world time cities
Time & place
Reminder
Phone finder
Exterior
Glass
Mineral Glass
Other
Neobrite
Watch Features
World time
World time
38 time zones (38 cities + coordinated universal time), city code display, city name display, daylight saving on/off, auto summer time (DST) switching, Home city/World time city swapping
Stopwatch
1/100-second stopwatch
Measuring capacity: 
00'00''00~59'59''99 (for the first 60 minutes)
1:00'00~23:59'59 (after 60 minutes)
Measuring unit: 
1/100 second (for the first 60 minutes)
1 second (after 60 minutes)
Measuring modes: Elapsed time, lap/split time
Timer
Countdown timer
Measuring unit: 1 second
Countdown range: 60 minutes
Countdown start time setting range: 1 second to 60 minutes (1-second increments and 1-minute increments)
Alarm/hourly time signal
5 daily alarms
Hourly time signal
Light
Double LED light
LED light for the face (Super illuminator, selectable illumination duration (1.5 seconds or 3 seconds), afterglow)
LED backlight for the digital display (Super illuminator, selectable illumination duration (1.5 seconds or 3 seconds), afterglow)
Light color
LED:White
Calendar
Full auto-calendar (to year 2099)
Mute feature
Button operation tone on/off
Energy saving feature
Power Saving (display goes blank to save power when the watch is left in the dark)
Battery display/alert
Battery level indicator
Run time
Approx. battery operating time:
7 months on rechargeable battery (operation period with normal use without exposure to light after charge)
18 months on rechargeable battery (operation period when stored in total darkness with the power save function on after full charge)
Accuracy
Accuracy: ±15 seconds per month (with no mobile link function)
Other features
Hand shift feature (Hands move out of the way to provide an unobstructed view of digital display contents.)
12/24-hour format
Date/month display swapping
Day display (days of the week selectable in six languages)
Regular timekeeping:
Analog: 2 hands (hour, minute (hand moves every 20 seconds)), 1 dial (battery level, mode)
Digital: Hour, minute, second, pm, month, date, day