Rémi D. 28/01/2026
| Reference Ocarat | #90305 |
| Reference | GA-B2100-1AER |
| Brand | Casio G-Shock |
| Product Type | Watch |
| Gender | Men |
| Color | Black |
| Material | Carbon Synthetic |
| Material Quality | Carbon fiber Resin |
| Warranty | 2 Years |
| Length (in mm) | 48,50 |
| Width (in mm) | 45,50 |
| Thickness (in mm) | 11,90 |
| Manufacturing | Japan |
| Warranty Type | International |
| Labels and Certificates | Authorized Retailer |
| Case Shape | Round |
| Case Weight (in g) | 52,00 |
| Bezel | Fixed Resin |
| Watch Case Back | Case back secured by screws |
| Crystal Shape | Flat |
| Glass Quality | Mineral Crystal |
| Buttons | 4 Push Buttons |
| Water Resistance (in ATM) | 20 |
| Movements | Solar |
| Calendar and Time | Dates Hours Minutes |
| Chronograph Function | Yes |
| Timekeeping and Measurement | 1/100th of a second chronometer Chronometer Chronometer - 24 hours Countdown |
| Alarm Complications | 12-Hour Alarm 24h alarm |
| Display Type | Analog (hands) Digital |
| Display Specifications | Arabic Numerals Indices and railroad track Super Illuminator |
| Techniques and Mechanics | Multifunctions: see description |
| Bracelet Material | Resin |
| Strap Color | Black |
| Water Resistant | Yes |
| Watch Clasp | Tang Buckle |
| Lug Width (in mm) | Special - Custom Made |
| Activities | Swimming / Diving Technical Adventure |
| Connectivity and Display | Bluetooth |
| Selection | Valentine's Day |
Whether you're hitting the gym or going about your daily routine, the Casio G-Shock GA-B2100-1AER is ready for anything. Its sleek black design and proportions - 45.50 mm wide, 48.60 mm tall, and 11.90 mm thick - make it a natural fit for men. Built to last, the carbon fiber-reinforced resin case is topped by a mineral crystal to shield the dial from every knock and scratch. At just 52 g, it sits on the wrist with barely-there comfort. Four pushers on either side of the case give you access to all the functions detailed below. The solar movement is sealed by a screw-secured case back, and with 20-atmosphere water resistance meeting the ISO 22810 standard, you're fully cleared for diving.
At the center of this round dial with a black background, you'll find two display types and a host of functions. First, a digital display nestled between 3 and 6 o'clock. Then, an analog display with two hands at the center of the dial showing hours and minutes in white and black. They point to grey baton indices along with a subtle minute track that complements the markers. The Super Illuminator function lights up the dial for easy reading in any situation. Finally, the brand signs its creation at 12 o'clock.
- Bluetooth® Smart: the watch is equipped with energy-efficient Bluetooth® technology, enabling data exchange with a single button press. The Bluetooth® function wirelessly connects the watch to a smartphone, unlocking a wide range of highly practical features.
- Smartphone Time: when the watch is paired with a smartphone, the time is set automatically and displays the current local time anywhere in the world.
- Super Illuminator: a single button press lights up the dial in vivid, on-trend colors.
- Shock Resistance: the shock-resistant structure protects the watch against impacts and vibrations.
- Neobrite Coating: the hands and/or indices feature a fluorescent coating that keeps glowing in the dark after the watch has been exposed to a light source.
- World Time Function: the world time function displays the time across 29 time zones and major cities around the globe.
- 1/100-Second Stopwatch - 24 Hours: measures elapsed time to 1/100th-second precision over a maximum duration of 24 hours. An audible beep confirms the start and stop of the stopwatch.
- Countdown Timers - 1/1 sec - 24 Hours: for those who love precision: countdown timers remind you of important or recurring events by sounding an alarm at the set date and time. The countdown can be programmed in seconds, up to 24 hours in advance.
- 5 Daily Alarms: an audible alarm reminds you of your daily commitments at the programmed time. This model features five independent alarms, giving you the flexibility to stay on top of all your important appointments.
- Button Beep On/Off: the button beep can be disabled using the mode button. Once turned off, no beep sounds when switching between functions. However, any programmed alarms or countdown timers remain active after the button beep is disabled.
- Hand Shift Function: this function moves the hands out of the way when they obscure the time, date, or stopwatch display.
- Phone Finder: misplaced your smartphone? Simply press one of the watch's buttons to trigger an alarm on your phone.
- Day of the Week Display in Multiple Languages: the day can be displayed in your choice of several languages.
- Auto Calendar: once set, the auto calendar always displays the correct date.
- 12/24-Hour Time Format: switch between 12-hour and 24-hour time display.
A solar movement powers this timepiece from within. The solar cells provide autonomous, self-sustaining energy, with any surplus stored in the rechargeable battery - an environmentally friendly solution.
The strap on this watch is made from black resin to match the case. Durable and flexible, it's built for sport while staying comfortable all day long. A silver-toned pin buckle lets you dial in the perfect fit.
With a water resistance of 20 atmospheres - 200 meters - this model qualifies without hesitation as a diving watch. Our watchmaking experts agree: it's more than up to the task for showering, bathing, lap swimming, freediving, and recreational scuba diving. That said, it's not designed for extreme deep-sea diving, where the pressure would exceed its limits. For professional divers chasing serious depths, we recommend models rated at 30 atmospheres and above. One final tip: avoid operating the pushers or crown while in the water to maintain a perfect seal.



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Customer reviews
Rémi D. 28/01/2026
Fabien P. 23/08/2025
David M. 07/01/2024
Black Solar Connected G-Shock Watch GA-B2100-1AER
(Ref. 90305)