Hands on Review: Casio G-Shock GA-B2100

In this “Hands on Review”, I am introducing the most recent evolution of the Casio G-Shock GA-2100 aka the “CASIOAK” watch. The model G-Shock GA-B2100 was launched in May 2022. This new member of the best-selling GA-2100 Analog-Digital family brings in advanced features such as Bluetooth connectivity and tough solar movement.

I have recently purchased a midnight blue variant (GA-B2100-2AER). The other versions presently available are: All Black (GA-B2100-1A1ER), Black with Grey (GA-B2100-1AER), Green (GA-B2100-3AER) and Yellow (GA-B2100C-9AER).

Hands on Review Casio G-Shock GA-B2100

Along with points of the hands on review of Casio G-Shock GA-B2100, I have also added some details related to various functions of the watch including smart-phone connectivity. This will be useful for those who are unfamiliar with “G-shock Connected” models.

G-Shock GA-B2100: Case, Dial and Strap


Boasting an eye-catching octagonal case design, the G-Shock GA-2100 has gained the nickname CASIOAK due to its resemblance with the iconic Audemars Piguet Royal Oak watch. The new Bluetooth Casioak retains the identical design. In fact, it comes with some technically advanced functions and features.

The GA-B2100 “CASIOAK Tough Solar” watch measures 48.5 × 45.4 × 11.9 mm and weighs 52gm. In comparison, GA-2100 is 1mm thinner and weighs 51gm. The new model maintains the sleek profile of GA-2100 Analogue-Digital series.

 Casio G-Shock GA-B2100 case

The materials used for the case and bezel remain same: Carbon and Resin. Fortified with a Carbon Core Guard structure, this watch is extremely shock resistant and has a water resistance of 200 meters. The case-back in steel is secured with four screws. The front glass is flat mineral crystal.

The GA-B2100-2AER model spotlights an eye-catching mid-night blue color case with contrasting steel pushbuttons.

 Casio G-Shock GA-B2100 case

On the case-back, you will find a multitude of inscriptions and numbers. The watch is robust yet lightweight, comfortable to wear and also looks great.

Push buttons

Casio GA-B2100 has four push buttons: A at 10 o’ clock, B at 2 o’clock, C at 8 o’clock and D at 4 o’clock. These buttons are used for operating various functions, and their roles vary depending upon the mode of operation selected by the user.

Casio G-Shock GA-B2100 Push buttons


The multi-layer dial of GA-B2100 features two large analogue hands at the centre, the model selector at the left side (between 8 and 10 o’clock markers) and a dual-window LCD display at the right-side (between 3 and 6 o’clock markers). The dial design is similar to that of G-Shock GA-2100, but has some functional differences.

The GA-B2100-2AER model comes with a grey color dial. Both the hour and minute hands are enhanced with the luminescent coating to make them visible in the dark. However, the indices are not lumed.

 Casio G-Shock GA-B2100 lume

The GA-2100 watch has a week of the day display near the 9 o’clock hour-marker whereas the new Casio G-Shock GA-B2100 model is provided with a mode selector/indicator at the same place.

Casio G-Shock GA-B2100 Dial

The mode selector features a hand to indicate various modes as inscribed on the arc shaped scale positioned on its right side. On this arc shaped scale, you will find eight markings: WT, ST, TR, AL, the Bluetooth icon, H, M and L. By pressing C button, the owner can select these modes.

WT stands for World Time, ST for Stop Watch, TR for Timer and AL for Alarm. The Bluetooth icon is for the smart phone connectivity mode. H, M & L respectively indicates High, Medium and Low charge levels of the solar rechargeable battery in the Timekeeping Mode.

Hands on Review Casio G-Shock GA-B2100

Above the LCD panel at 3 o’clock, the dial of Casio G-Shock GA-B2100 contains inscriptions “TOUGH SOLAR” and “Bluetooth” where as GA-2100 has “WR 20 BAR” text.

GA-B2100’s Digital display features status indicators for Alarm (ALM) , Hourly Time Signal (SIG) , Connectivity with Smart Phone (RCVD) , Reminder (REM) and Hand-Shifting Function (HND). In comparison, GA-2100 has indicators for MUTE, ALM, SIG, DST and HND.

Hands on Review Casio G-Shock GA-B2100

Reading out the information shown on the digital display is somewhat tricky due to its miniature size. It is also difficult to read the markings on the mode selector scale.

An illumination system helps to glance at the LCD panel during low visibility conditions. It can be activated by the B button of the watch. The illumination duration can be set to either 1.5 seconds or 3 seconds.


The wristband of GA-B2100-2AER is made of resin. Featuring the same color of the case, it has a stainless steel pin buckle. The two-part strap is properly secured to the case-body with steel screws, offering seamless fitting.

Casio G-Shock GA-B2100 Strap

The watch also features strap release mechanisms with a protector at the lug ends. Thanks to this flexible yet strong band, the G-Shock GA- B 2100 is extremely comfortable to wear.

Power source

The Casio G-Shock GA-2100 is powered by a quartz movement with an approximate battery life of three years. The new GA-B2100 Bluetooth watch however comes with a Tough Solar movement. The power is supplied from a rechargeable battery that is charged by a solar panel integrated into the face of the watch. The charging levels (L, M and H) are indicated by the mode hand in the Timekeeping Mode.

Hand shifting feature

The analogue hands of hour and minute sometimes hinder the view of LCD display. To read the digital indications without any obstruction, GA-B2100 offers a Hand Shifting function. It can be activated by pressing C button while holding B. Both hour and minute hands will be shifted to an alternative position, allowing the user to clearly read the information shown on the digital display.

Casio G-Shock GA-B2100 Hand shifting feature

To bring back the analogue hands to its normal timekeeping position, hold down the B button and press C again. It is to be noted that the hands will automatically go to the original place if you do not perform any operation for about one hour.

G-Shock GA-B2100: Smartphone Connectivity

The Casio G-Shock GA-B2100 model can be connected to a smart phone using Bluetooth wireless technology. Pressing the C button continuously for at least 3 seconds will activate the Bluetooth function of the watch.

You should also switch on the Bluetooth link of the smartphone for pairing. I have paired my GA-B2100 with an android smart-phone loaded with CASIO WATCHES App without any issue. The signal range is however limited (less than two meters).


To utilize the smart features of GA-B2100, you need to install the CASIO WATCHES App on your smartphone. This application is compatible with Android (version 8.0 or later) and iOS (iOS 13.0 or later) based phones. Depending upon your mobile OS, you may download the App from Google play store or Apple App store.

Smartphone Connectivity

With this App, the user can easily adjust the setting of GA-B2100 via Bluetooth link. The same app can also be used with Casio G-Shock MRG-B5000 & GST-B500, Oceanus OCW-S6000 & OCW-T5000 and Edifice ECB-30 models.

During the installation of the App, you need to enter a CASIO ID to register the phone. Therefore before downloading the App, please register your watch and obtain the login details by visiting casio.com. Once the App installation is completed, switch on the Bluetooth function of the smart phone.

For pairing your Casio GA-B2100 with a smartphone, you need to activate Bluetooth mode. Place the watch near the phone (within one meter distance) and press the pushbutton C for at least three seconds. The digital display will start flashing CNCT and the mode selector hand will move and point to the Bluetooth icon.

Casio G-Shock GA-B2100 Smartphone Connectivity

When the connection between the watch and phone established, CNCT will stop flashing. Repeat the operation if the display shows ERR (error). Once pairing is complete, the CASIO WATCHES App on your smart phone show the status as connected.

Smartphone Connectivity

The App displays menus like Alarms, Timer, Reminder, World Time, Home Time, Time Synchronization, Manual Hand Adjustment, Phone Finder, Watch Settings and Tutorial. With these you can access and set various functionalities of the GA-B2100 from the smartphone.

G-Shock GA-B2100: Functions

Timekeeping Mode

It is the default mode of GA-B2100. In the Timekeeping Mode, the two analogue hands indicate the hours and minutes. When the watch is not paired with a smartphone, the upper-section of the LCD panel indicates the running seconds and the lower-section shows the date, month and day of the week.

Casio G-Shock GA-B2100 Timekeeping Mode

When the watch is paired with a phone, the lower-window of LCD also displays REM (indicating reminders if any). With pushbutton A, you can toggle between the details indicated on the digital screen.

Casio G-Shock GA-B2100 Timekeeping Mode

In the Time Keeping Mode, the mode selector hand points to H, M or L depending upon the charge level of the battery of Casio Tough Solar movement of the watch.

Auto Time Adjustment

Whenever you pair GA-B2100 with a smartphone, the time-setting is adjusted automatically. Moreover, your watch will connect to the phone over the Bluetooth link and carry out automatic time setting four times a day (at around 12.30 a.m., 6.30 a.m., 12.30 p.m., and 6.30 p.m.). Soon after the successful completion of automatic time adjustment on each occasion, the watch will automatically terminate the wireless connectivity with the phone.

Stopwatch Mode

In the Stopwatch mode, Casio GA-B2100 performs chronograph functions including measurement of Elapsed, Split and Lap times. It indicates the measurements on the lower part of the LCD panel. The stopwatch measures elapsed time in 1/100 second units for the first one hour and in 1 second/units after that for up to 24 hours.

Casio G-Shock GA-B2100 Stopwatch Mode

Operate the button C to move the mode selector hand to ST (Stopwatch mode). With the button D, the user can perform the start, stop and resume functions of the elapsed time measurement. Press (A) button to reset the stopwatch to all zeros.

For measuring Split and Lap times, use D and A buttons: (D) for Start & Stop functions and (A) for calculating split/lap time. The stopwatch function is not configurable with the CASIO WATCHES App.

Countdown Timer Mode

Again, use the C button to position the mode selector hand pointing to TR (timer mode). The countdown start timer can be set in one-second units up to 60 minutes on the lower panel of digital display.

For setting the timer, press (A) for at least two seconds. Both the hour and minute hands now move to a position to provide the full view of the digital display.

Casio G-Shock GA-B2100 Countdown Timer Mode

When the minute digits start flashing on the LCD, release (A) and use push-buttons B and D to set the minutes. After setting the minutes, press (C) and the seconds digits began flashing. In this case also, use (B) and (D) to set the seconds. Press (A) to exist from the setting. The countdown timer can also be configured with CASIO WATCHES App on your smartphone.

For using the Countdown function, press (D). The same button is also utilized for pausing and resuming the timer. The watch beeps for 10 seconds to notify the user when the end of a countdown is reached. Press any button to stop the tone.


With this function, you can create reminders for an event associated with your personal or professional life. In the GA-B2100 model, reminders can be set by using CASIO WATCHES App only.

Before setting the reminder, pair the watch with your smart phone by pressing the C button continuously for three seconds. Once the connection is established, select the Reminder function from the menu of CASIO WATCHES App installed on your smart-phone. You can create up to five different reminders at a time.


You can set a reminder by entering the title (for example birthday, appointment or any other event), frequency (only once, weekly, monthly, yearly or a certain period) and date. After setting the reminder save it and send to your GA-B2100.

After transferring the reminder data to watch, the REM indicator will appear on the digital display. Press button A to view the details of reminders saved into the watch.

If you have any reminder for today, the lower section of the LCD panel will begin flashing REM. Press the button A, and GA-B2100 will display the reminder for the day on the digital screen.

Alarm Mode

With this function, you can set up to five different alarms on your GA-B2100 watch. The alarm function can be configured by operating pushbuttons or using CASIO WATCHES App installed on your smart-phone.

The watch will produce a beep sound for ten seconds when an alarm time is reached. To configure alarm, you have to set the mode selector hand to AL mode. Use the button C for selecting the Alarm mode and (D) to scroll through alarm numbers (AL1 to AL5) until the alarm you want to configure is displayed.

Then hold (A) for at least two seconds. Release the button when the hours digit start to flash. At the same time, the hour and minute hands move to a new position so that the digital display is visible without any obstruction.

Casio G-Shock GA-B2100 Alarm Mode

Use buttons B or D to set the hour. After that press C, the minutes digits will start to flash and use B or D to set the minutes. Finally, press A to complete the Alarm configuration. Now the upper section of the digital panel will display ALM indicator. The Alarm function of GA-B2100 can also be set with CASIO WATCHES App installed on your smartphone.

Alarm Mode

With the Hourly Time Signal function enabled, the watch beeps to indicate every passing hour. To facilitate this functionality, enter the Alarm mode and press button D to display the hourly time signal (SIG) screen. Operate the button A to enable or disable the function.

The SIG indication on the upper LCD panel will display once the Hourly Time Signal is switched on. This utility can also be configured by CASIO WATCHES App when the watch is paired with a smartphone.

World Time Mode

The World Time function of GA-B2100 allows the user to find the current time of in any one of 38 cities around the globe and UTC (Coordinated Universal Time). To read the current time of a selected world city, enter into the World Time Mode by operating the C button and then press button A. The mode selector hand displays WT during the World Time Mode.

Casio G-Shock GA-B2100 World Time Mode

The World Time function can also be configured by CASIO WATCHES App on your smartphone over the Bluetooth link.

The World Time utility of the App allows you to select from among approximately 300 cities from the map as your Word Time city. You can use the app to configure settings for the cities that are not included in the watch’s built-in World Time cities.

World Time Mode

The watch allows you to swap your World Time and Home Time when moving to another time-zone. This function can be performed manually or by using CASIO WATCHES App. It should be noted that Auto Time Adjustment does not work for 24 hours after swapping of the Home Time and World Time. You can also configure Summer Time setting manually or with the App.

Adjusting Hand Alignment

If the analogue hands are out of alignment even though auto time adjustment is being performed, you can precisely adjust them by operating the manual hand-setting utility of CASIO WATCHES App.

manual hand adjustment

Recording the Current location

GA-B2100 is capable of recording the current location (longitude and latitude) along with the date and time. Pressing the D button in Time Keeping Mode records the above details and instantly transfers to the phone memory over Bluetooth link.

Recording the Current location

The recorded locations including the date and time can be viewed on a map in the “My Page” section of the CASIO WATCHES App on your smart phone. You can also delete these details using the App.

Other functions

With CASIO WATCHES App, GA-B2100 also offers various other functions like Phone Finder, changing the Home City Summer Time setting, and checking the watch charge level.

Watch Settings

With the Watch Settings menu of CASIO WATCHES App, you can adjust the Key Sounds, Light (duration of dial illumination) , Watch Display (in 12 or 24 h format, day of week language and order of the month and date) , Power Saving, Change Time Display and Connection time with the app (3, 5 or 10 minutes).

Manual settings

Many settings of GA-B2100 can be performed without the help of CASIO WATCHES App. But it is a cumbersome job, especially when you carry out the time and date settings. Using the App avoids such complex manual-setting procedures.

G-Shock GA-B2100 Price

The retail price of Casio G-Shock GA-B2100 is approximately US$150. It is now available for purchase at Watches.com