Carbon Core Guard structure
Ever since the first DW-5000C went on sale back in 1983, G-SHOCK has continued to push the limits of timekeeping toughness while creating new and original designs. These new models embody these efforts in an attractively thin configuration.
These new models inherit the octagon form that was also employed for the original DW-5000C. Analog-digital timekeeping comes packed into a no-nonsense simple design without sacrificing G-SHOCK level toughness.
High-strength resin material, which is reinforced with carbon fibers, makes it possible to create a case that is a mere 11.8 mm thin, which is the thinnest among G-SHOCK combination models.

Features

Case / bezel material: Carbon / Resin　
Resin Band
Mineral Glass
Shock Resistant
Carbon Core Guard structure
200-meter water resistance
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)
World time
31 time zones (48 cities + coordinated universal time), daylight saving on/off
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, split time, 1st-2nd place times
Countdown timer
Measuring unit: 1 second
Countdown range: 24 hours
Countdown start time setting range: 1 second to 24 hours (1-second increments, 1-minute increments and 1-hour increments)
5 daily alarms
Hourly time signal
Hand shift feature
Full auto-calendar (to year 2099)
12/24-hour format
Button operation tone on/off
Regular timekeeping
Analog: 2 hands (hour, minute (hand moves every 20 seconds)), 1 dial (day)
Digital: Hour, minute, second, pm, month, date
Accuracy: ±15 seconds per month
Approx. battery life: 3 years on SR726W × 2

Casio G-Shock GA-2100-4A