Apart of the ‘Black & Rust Colour’ collection, GA2100RC-1A is an example of the level of toughness the G-SHOCK watches can withstand. In demonstration of the colour of aged metal over time.

- 48.5 × 45.4 × 11.8mm Case Size
- 51g Weight
- Carbon/Resin Case and Bezel
- Resin Band
- Shock Resistant
- Carbon Core Guard structure
- 200 Meters Water Resistant
- Approx. battery life: 3 years on SR726W X 2
- Mineral Glass
- World time: 31 time zones (48 cities + coordinated universal time), daylight saving on/off
- Stopwatch
- Timer
- Alarm/hourly time signal
- Double LED light
- 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 (Hands move out of the way to provide an unobstructed view of digital display contents.)
- Regular timekeeping:
Analog: 2 hands (hour, minute (hand moves every 20 seconds)), 1 dial (day)
Digital: Hour, minute, second, pm, month, date