The Casio G-SHOCK Gravitymaster Bluetooth Tough Solar GR-B300-8A2ER is a versatile men's watch designed for extreme activity enthusiasts. The watch is equipped with a solar mechanism, and its gray carbon envelope and rubber strap are reinforced with fiberglass and stainless steel. The black dial with turquoise elements and Neobrite coating provides excellent visibility. The watch has features such as day alarm, crown lock, Bluetooth Smart, Dual Time Display, Flight Log Memory, world time function, Smartphone time, Super Illuminator, shockproof system, timer, charge indicator and lost phone function. Water resistance up to 200 meters makes it a reliable choice for those with active lifestyles.
Functions
Bluetooth® Smart
The watch is equipped with energy-saving Bluetooth® technology, which offers power-saving data transfer at the push of a button. The watch can connect to a smartphone wirelessly via Bluetooth®, enabling access to a wide range of useful functions.
Super-Illuminator
At the touch of a button, the display can be brightly illuminated in a fashionable color
Shock-resistant
Shock-resistant construction protects against impact and vibration.
Solar Power
A solar cell provides power for operation.
Neo-display
A luminous coating provides long-term illumination in the dark after only a short exposure to light.
World time function
Displays the current time in major cities and specific areas around the world.
Date and weekday display
The current day and weekday are both displayed.
Stopwatch function - 24 hours
Elapsed times are measures with split-second accuracy. The watch can measure times of up to 24 hours.
Timer - 1/1 min. - 24 hours
For fans of precision: the countdown timers help you to remember specific or recurring events by giving off an audible signal at a preset time. The time can be set to the nearest seconds and up to 24 hours in advance. This model has three independent timers - ideal for people who need to take medicines every day or those who do interval training.
Daily alarm
The daily alarm reminds you of events that recur every day, by emitting an audible signal at the set time.
Crown button lock
Secures the crown button from accidental change to another mode of operation.
Phone Finder
Misplaced your smartphone? All it takes is the push of a button on your watch and the smartphone sounds an alarm.
Flight Log Memory
The product is equipped with Flight Log Memory.
Mineral glass
The tough mineral glass resists damages.
Folding clasp
The watch has a folding clasp.
Battery level indicator
An indicator shows the current battery level.
Water resistance classification (20 bar)
Perfect for free diving without scuba gear: the watch is water resistant up to 20 bar according to ISO 22810.
What’s in the box?
3-year warranty
User manual
Warranty card
Casio box
Reviews about G-SHOCK Gravitymaster Bluetooth Tough Solar GR-B300-8A2ER (5)
This G-SHOCK Gravitymaster is a real beast on the wrist. You can tell right away that this is a watch built for tough jobs—the carbon case makes a great impression; it’s incredibly sturdy, yet lighter than I expected given its size. The design with turquoise accents on the black dial looks very modern and professional, definitely standing out from other models. From a technological standpoint, it’s perfect for me. Tough Solar solves the battery problem, and Bluetooth allows for instant time synchronization and access to features via a phone app. The Flight Log feature is very useful, allowing you to record your location, which is a great addition for people who enjoy traveling and logging routes. The Super Illuminator backlight and Neobrite coating make reading the time at night a breeze. It’s a watch that not only looks great but gives you the feeling that it will survive any adventure.
Lucek
2/5/26
100%
It was worth waiting those dozen or so hours for the delivery, because the quality of the product I received exceeded my wildest expectations.
Kajra
1/1/26
100%
I bought a watch that perfectly combines durability with comfort. I especially appreciate the gray rubber strap, which is very practical. The product meets my expectations—I highly recommend it.
RADHAKRISHNAN NAIR
12/6/25
100%
I received a G-SHOCK watch as a gift, and I'm happy with it. The watch looks sturdy and modern.
Joker
8/2/24
100%
I bought a G-SHOCK watch and I’m incredibly happy with my purchase. The rubber strap is a total hit—it’s comfortable, flexible, and fits my wrist perfectly, which is essential for me during my daily activities. Additionally, I have to give the store credit for the convenient product availability notification, which made the purchase completely hassle-free. I definitely recommend this watch—5/5 stars!
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The administrator of your personal data is the owner of the Watchard store, i.e. 57 Concepts Sp. z o.o. Sp. k. with the registered office at al. Witosa 31, lok. 115, 00-710 Warsaw, Poland. Providing personal data by the Customer is voluntary but necessary to complete the purchase. You have the right to view your personal data we have processed, as well as the right to request changes or removal of your personal data. Personal data will be processed for a period of 10 years.
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The administrator of your personal data is the owner of the Watchard store, i.e. 57 Concepts Sp. z o.o. Sp. k. with the registered office at al. Witosa 31, lok. 115, 00-710 Warsaw, Poland. Providing personal data by the Customer is voluntary but necessary to complete the purchase. You have the right to view your personal data we have processed, as well as the right to request changes or removal of your personal data. Personal data will be processed for a period of 10 years.
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