G-SHOCK GA-2100-9A9ER

The GA-2100-9A9 is the volt yellow edition of the CasiOak — G-SHOCK’s slim, octagonal-bezelled icon that redefined what a tough watch could look like when it launched in 2019. Head-to-toe yellow covers the case, bezel, dial, hands and band in a monochrome tone-on-tone scheme where subtly different shades create depth and dimension across every component.

Underneath the bold exterior sits the Carbon Core Guard structure, where a carbon fibre-reinforced resin case protects the module while keeping the profile to just 11.8 mm thick. The bezel and band are made from bio-based resin derived from renewable organic resources, reducing environmental impact without compromising on G-SHOCK toughness. At only 51 grams, the watch is featherlight on the wrist.

The three-dimensional dial features a notched dial ring, cut index marks and a small digital LCD window that handles world time, stopwatch, timer and alarm functions. Neobrite-treated hands stay visible after dark, backed by a Double LED light system — one Super Illuminator for the analogue face and a separate LED backlight for the digital display. Full G-SHOCK functionality includes a 1/100-second stopwatch, world time, countdown timer, five daily alarms and hand shift feature.

Basic Information

Case size (L× W× H): 48.5 × 45.4 × 11.8 mm
Weight: 51 g
Case and bezel material: Carbon / Bio-based resin
Band: Bio-based resin band
Construction: Shock Resistant, Carbon Core Guard structure
Water resistance: 200-metre water resistance
Power supply and battery life: Approx. battery life: 3 years on SR726W × 2

Exterior

Glass: Mineral Glass
Compatible band size: 145 to 215 mm
Other: Neobrite

Watch Features

World time: 31 time zones (48 cities + Coordinated Universal Time), daylight saving on/off
Stopwatch: 1/100-second stopwatch, Measuring capacity: 00’00”00 to 59’59”99 (for the first 60 minutes) 1:00’00 to 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
Timer: 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)
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)
Calendar: Full auto-calendar (to year 2099)
Mute feature: Button operation tone on/off
Accuracy: ±15 seconds per month
Other features: 12/24-hour format, Hand shift feature
Regular timekeeping: Analogue: 2 hands (hour, minute (hand moves every 20 seconds)), 1 dial (day); Digital: Hour, minute, second, pm, month, date