The GR-B300-8A2 is part of the GRAVITYMASTER line within G-SHOCK’s MASTER OF G – AIR series, designed as aviation-inspired professional gear built for the harshest environments. The Carbon Core Guard structure uses carbon fiber-reinforced resin — a material also found in aircraft fuselages — delivering shock resistance, rigidity, and corrosion resistance. The seamless bezel design inspired by next-generation aircraft creates an organic, unified form from case to band that embodies cutting-edge toughness. The large-diameter, triple-layer dial with dimensional index marks and instrument panel-inspired inset dials ensures intuitive readability essential for pilots. A rotary disc indicator at 9 o’clock uses a dual-coil motor for smooth rotation, displaying battery level, alarm status, and mode-linked motion. Dual time simultaneously shows the time in two cities, while the flight log function records current time and position via the CASIO WATCHES app. Powered by Tough Solar with Bluetooth Smartphone Link for automatic time adjustment, the high-contrast dark colorway with blue accents evokes a cockpit head-up display. Bio-based resin components in the case, bezel, and band reduce environmental impact. Basic Information Case Size (L× W× H): 59 × 54.7 × 15.7 mm Weight: 71g Case and Bezel Material: Bio-based Carbon / Bio-based resin Band: Bio-based 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: Tough Solar (Solar powered) Smartphone Link Connectivity: Mobile link (Wireless linking using Bluetooth®) App: CASIO WATCHES App Features: Auto time adjustment, Easy watch setting, Approximately 300 world time cities, Flight log, Phone finder Exterior Glass: Mineral Glass Crown: Screw Lock Crown Compatible Band Size: 145 to 215 mm Other: Neobrite Watch Features World Time: Dual time (Home City time swapping) Stopwatch: 1-second stopwatch, Measuring capacity: 23:59’59, Measuring modes: Elapsed time, split time Timer: Countdown timer (1 minute to 24 hours) Alarm: Daily alarm Light: LED light (Super Illuminator), Afterglow Light Color: LED: White Calendar: Full auto-calendar (to year 2099) Energy Saving: Power Saving (hands stop in the dark) Battery Display: Battery level indicator Run Time: Approx. 5 months (normal use without light exposure), 18 months (power save after full charge) Accuracy: ±15 seconds per month (with no mobile link function) Other Features: Date display Day indicator
