The CASIO G-SHOCK GRAVITYMASTER GR-B300 is an aviation-inspired analog watch with Tough Solar charging, Bluetooth smartphone linking, dual time and a flight-log utility that records time and position through the connected CASIO WATCHES app. Its three initial color variants share the documented feature set; the main choice is which dial design you prefer. Casio presents the series for aviation enthusiasts, but the available manufacturer documentation does not establish aviation certification or professional endorsement of the finished watch.
What is the GR-B300?
GRB300 is Casio’s G-SHOCK GRAVITYMASTER GR-B300 series, an analog watch line designed around aviation-inspired styling. Casio announced three initial references in the United States on May 15, 2024: GRB300-1A, GRB300-1A4 and GRB300-8A2. The company also writes the model name with a hyphen as GR-B300.
Casio says its design development included interviews with professional pilots. That describes the design process, not a certification or endorsement of the watch for professional cockpit use.
What features does the GR-B300 provide?
Timekeeping and smartphone connection
The watch has two time displays: the main dial and an inset dial show the time in two cities or time zones. Casio’s US series page says the CASIO WATCHES app can configure world-time settings and swap home and world time. The page also lists automatic time adjustment four times a day and world time for about 300 cities; these are stated app capabilities, not guarantees about phone compatibility or service in every region.
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#1 Best Overall
- Water Resistant
- Stylish and Modern Design
- Durable and Safe Material
- Resin band
Tough Solar provides solar-powered charging, while Bluetooth links the watch to a smartphone. Casio also lists easy settings and a phone-finder feature through the app.
Flight log
When paired with a smartphone, a button press on the watch records the current time and position for display on a map in the app. Casio describes grouping plotted data to manage travel history. Treat this as a watch-and-app recordkeeping utility, not as a certified navigation system, flight instrument or cockpit log. Casio’s product description cautions that app specifications were not final when it was published, so specific app behavior may change.
Rank #2
- The sky's the limit! Introducing the Casio G-Shock GRAVITYMASTER GRB300, a piece of aviation-inspired professional gear designed to work even in the harshest environments, from the Master of G line.
- This watch features a Carbon Core Guard structure, which delivers the shock-resistance, rigidity, and corrosion-resistance of carbon material used in aircraft fuselages.
- 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.
Everyday functions and construction
- Durability: Casio lists shock resistance and 200-meter water resistance.
- Display: A Super Illuminator LED provides illumination, and the watch displays the date and day.
- Timing: It includes a stopwatch, countdown timer and alarm.
- Materials: Casio specifies a carbon-fiber-reinforced resin case and bio-based resin in key resin components. The material description alone does not establish the watch’s overall lifecycle impact.
How the aviation-inspired design works
The prominent dial uses three layers, raised indices and contrasting colors. A rotary indicator adds a further instrument-like element. Casio connects these choices to cockpit-inspired styling and legibility, but its claims are design intent rather than independent measurements of readability.
The color treatments draw on different visual references: the black-and-white base emphasizes contrast, the red-accent design nods to cockpit instrument lighting, and the blue accent evokes a head-up display. Those are Casio’s descriptions of the inspiration, not evidence that one version performs better in a cockpit.
Rank #3
- Super Matte Finish, Shock Resistant, 200M water resistance, LED light (Super illuminator), World time, Stopwatch, Countdown timer, 5 daily alarms, Hourly time signal, Hand shift feature
- Full auto-calendar, 12/24-hour format, Analog: 2 hands (hour, minute (hand moves every 20 seconds)), Digital: Hour, minute, second, pm, month, date, day, Approx. battery life: 5 years on CR2016
- Quartz Movement
- Case Diameter: 52.8mm
- Water resistant 200m (660ft): in general, suitable for professional marine activity and serious surface water sports, but not diving
Which GR-B300 variant should you choose?
| Reference | Documented design distinction | Documented functional difference |
|---|---|---|
| GRB300-1A | Black-and-white base scheme, associated by Casio with contrast | None identified in the available Casio material |
| GRB300-1A4 | Red accents, inspired by cockpit instrument lighting | None identified in the available Casio material |
| GRB300-8A2 | Blue accent, inspired by a head-up display | None identified in the available Casio material |
The documented distinction among these launch models is color and dial styling; Casio’s cited material does not identify different functions. Confirm the exact reference on a seller’s listing, particularly if color matters, and check current price and stock directly because availability has not been verified here.
How it differs from the GR-B200
Casio describes the GR-B300 as a return to a fully analog display: it replaces the GR-B200’s digital display window with an inset dual-time display. Casio’s editorial feature also says the GR-B300 is approximately 4 mm shorter from 12 to 6 o’clock and 2.8 mm thinner than the GR-B200. Those are manufacturer-reported comparisons, not independent measurements. They offer a useful size and display distinction, but not a complete feature-by-feature comparison.
Rank #4
- Band Size: Mens-Standard
- Shock Resistant
- Auto LED Light with Afterglow
- Magnetic Resistant
Price and availability
Casio America announced a launch price of $300 for each initial model at select US sellers in May 2024. That is historical launch pricing, not a current quote. The announcement named select jewelers, department stores, gshock.com and the G-SHOCK Soho store as initial sales channels; it does not confirm present inventory or pricing.
Quick Recap
Best Value
- Rugged & Sporty Design – Matte black finish with bold digital display, built for tactical, military, and extreme sports enthusiasts.
- High-Brightness LED Backlight – Features Super Illuminator LED with a light guide plate, ensuring exceptional visibility in low-light conditions.
- 200M Water Resistance – Engineered for swimming, snorkeling, and outdoor adventures, this shock-resistant watch is ready for action.
- Extended 7-Year Battery Life – Powered by a CR2025 battery, offering years of reliable performance without frequent replacements.
- Shock-Resistant Structure – Built to withstand extreme conditions, making it ideal for sports, military, and rugged outdoor use.
Sources
- Casio US GR-B300 series specifications
- Casio America’s May 15, 2024 GR-B300 announcement
- Casio international GR-B300-8A2 product page
- Casio G-SHOCK GR-B300 design feature
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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