Japan Treasure Factory
Casio G-SHOCK GR-B300H-5AJF GRAVITYMASTER — Bluetooth Tough Solar Carbon Core Guard
Casio G-SHOCK GR-B300H-5AJF GRAVITYMASTER — Bluetooth Tough Solar Carbon Core Guard
Couldn't load pickup availability
G-SHOCK GRAVITYMASTER GR-B300H — Master in Horizon Gold
MASTER OF G - AIR line / Released August 2026
The GR-B300H-5AJF is part of the G-SHOCK MASTER OF G series' new "Master in Horizon Gold" design, inspired by the golden horizon where earth meets sky. The GRAVITYMASTER GR-B300H combines light yellow gold IP and brown IP accents with a dark brown resin band to express the raw power of nature. It features Carbon Core Guard construction, pairing a carbon-fiber-reinforced resin case with a seamless bezel inspired by next-generation aircraft for a bold, resilient form.
This model includes a home-time swap function and a dual time function, useful for overseas travel. Large, three-dimensional hour markers and a metal bezel that emphasizes the wide face improve visibility and functionality. A dual-coil motor drives the disc hand at the 9 o'clock position, adding rotational expression for the alarm on/off indicator, stopwatch, and battery indicator. It does not include sensors — no compass, no altimeter/barometer, and no thermometer.
Specifications
| Model | GR-B300H-5AJF |
| Series | G-SHOCK MASTER OF G - AIR / GRAVITYMASTER |
| Case size | 59 × 54.7 × 15.7 mm / 2.32 × 2.15 × 0.62 in |
| Weight | 71 g / 2.5 oz |
| Case / bezel material | Carbon fiber reinforced resin (biomass plastic) / resin (biomass plastic) / stainless steel |
| Band | Resin band (biomass plastic) |
| Glass | Mineral glass |
| Water resistance | 20-bar (200-meter) |
| Structure | Shock resistant, Carbon Core Guard structure |
| Time correction | Bluetooth (auto time correction via smartphone) |
| Power source | Tough Solar |
| Mobile Link / App | CASIO WATCHES app — auto time correction, easy watch setting, world time (approx. 300 cities), flight log, phone finder |
| Functions | World time, Dual time (with home time swap), Stopwatch (1-sec, 24-hr, split), Timer (1-min unit, max 24 hr), Time alarm, LED light (Super Illuminator with afterglow), Full auto calendar, Power saving function, Battery indicator |
| Battery life | ~5 months (with functions) / ~18 months (power saving) |
| Band size | 145–215 mm |
| Release date | August 2026 |
Share
