G-Shock Gravitymaster GRB300-1A

The GR-B300 features a Carbon Core Guard structure, which delivers the shock-resistance, rigidity, and corrosion-resistance of carbon material used in aircraft fuselages. The carbon fibre-reinforced resin case and the seamless bezel design inspired by next-generation aircraft come together in a bold and powerful form.

Envision the world through a pilot’s eyes with the flight log memory function for recording current location and time, as well as dual-time simultaneously displaying the time in two time zones. In addition, simply tap on the app to instantly switch between the time back home and local time — a practical function to make traveling abroad that much smoother.

Large, dimensional index marks and a metal bezel accentuating the large watch face exude functionality, enhancing the visibility that is so important for pilots, whose job demands intuitive reading of time.

The rotary disc indicator at the 9 o’clock position uses a dual-coil motor to ensure smooth rotation and functional beauty. The indicator not only rotates to display alarm on/off and stopwatch; it functions as a battery level indicator as well.

The high-contrast black and white colour scheme dotted with colour accents on the dial and buttons evokes the look of a cockpit instrument panel, while dark colour variations express the practical functionality of an aviation worldview.

Key resin components used in the case, bezel, and band are made with bio-based resin, a material expected to help reduce environmental impact.

• Case / bezel material: Carbon
• Resin Band
• Neobrite
• Vibration resistant
• Shock Resistant
• Mineral Glass / Spherical Glass
• 200-meter water resistance 
• Double LED light
  LED light for the face (Auto LED light, Super illuminator, selectable illumination duration (1.5 seconds or 3 seconds), afterglow)
  LED backlight for the digital display (Auto LED light, Super illuminator, selectable illumination duration (1.5 seconds or 3 seconds), afterglow)
• Mobile link (Wireless linking using Bluetooth®)
• Digital compass
  Measures and displays direction as one of 16 points
  Measuring range: 0 to 359°
  Measuring unit: 1°
  60 seconds continuous measurement
  Hand indication of north
  Magnetic declination correction
  Direction calibration (2-point calibration, figure eight calibration, auto calibration)
• Altimeter
  Measuring range: –700 to 10,000 m (–2,300 to 32,800 ft.)
  Measuring unit: 1 m (5 ft.)
  Hand indication graph of altitude differential
  Manual memory measurements (up to 14 records, each including altitude, date, time)
  Auto log data (High/low altitudes, cumulative ascent and descent)
  Others: Relative altitude readings (±100 m /±1000 m), selectable measurement interval: 5 seconds or 2 minutes (1 second for first 3 minutes only)
  *Changeover between meters (m) and feet (ft)
• Barometer
  Measuring range: 260 to 1,100 hPa (7.65 to 32.45 inHg)
  Measuring unit: 1 hPa (0.05 inHg)
  Hand indication of pressure differential (±10 hPa)
  Atmospheric pressure tendency graph (last 20 hours or last 56 hours)
  Barometric pressure tendency information alarm (beep and arrow indicates significant changes in pressure)
  The atmospheric pressure tendency graph can show the last 20 minutes or last 56 minutes of measurements.
  The hand indication of pressure differential shows values in units of ±1 hPa.
  *Changeover between hPa and inHg
• Thermometer
  Measuring range: –10 to 60°C (14 to 140°F)
  Measuring unit: 0.1°C (0.2°F)
  *Changeover between Celsius (°C) and Fahrenheit (°F)
• Step count using a 3-axis acceleration sensor: 0 to 999,999 step count display range
  Power Saving: Auto sensor sleep state entry after fixed period of non-activity
• World time
  38 time zones (38 cities + coordinated universal time), daylight saving on/off, Home city/World time city swapping
• Sunrise, sunset time display
  Sunrise time and sunset time for specific date
• 1/100-second stopwatch
  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-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: 3 hands (hour, minute (hand moves every 10 seconds), second)
  Digital: Hour, minute, second, am/pm, month, date, day
• Accuracy: ±15 seconds per month (with no mobile link function)
• Approx. battery life: 2 years on CR2025
• Size of case : 63×54.1×18.3mm
• Total weight : 80g

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