Casio G-Shock GA-2100RC-1A Black and Rust Resin Digital Watch

The Casio G-Shock GA-2100RC-1A is a black and rust digital quartz watch built for men who want a tough everyday timepiece with a distinctive industrial look. Its carbon and resin case, resin band and rust-inspired sepia and light blue accents set it apart from a plain sports watch.

The watch pairs a 48.5 × 45.4 × 11.8 mm carbon and resin case with a resin band that uses Carbon Core Guard structure for added strength. At 51 g it stays light on the wrist, while mineral glass helps protect the face from scratches. A 200-meter water resistance rating covers swimming and snorkeling, and world time spans 31 time zones (48 cities plus UTC) with daylight saving on or off. The 1/100-second stopwatch, 24-hour countdown timer, five daily alarms and hourly time signal support training, travel and daily schedules.

Key features and benefits of the Casio G-Shock GA-2100RC-1A

• Carbon and resin case with Carbon Core Guard band: The case measures 48.5 × 45.4 × 11.8 mm and weighs 51 g, so it is built to take knocks without feeling heavy. The resin band uses a Carbon Core Guard structure for strength and flexibility.
• Mineral glass: Mineral glass covers the dial and resists everyday scratches. It helps the watch stay clear through regular wear.
• 200-meter water resistance: The rating suits swimming, snorkeling and water sports. It is not intended for diving.
• World time: World time covers 31 time zones, 48 cities plus UTC, with daylight saving on or off. Travellers can check another city without resetting the main time.
• 1/100-second stopwatch: The stopwatch measures up to 24 hours and records elapsed time, split time and 1st-2nd place times. The first 60 minutes read to 1/100 second, then to 1 second.
• Countdown timer: The timer counts down from 1 second to 24 hours in 1-second, 1-minute or 1-hour steps. It gives a clear way to time intervals or a reminder.
• Five daily alarms and hourly signal: Five daily alarms plus an hourly time signal keep reminders close. You can set alerts for separate parts of the day.
• Double LED light: A double LED light illuminates the face and digital display, with a 1.5 or 3 second duration and afterglow. It helps you read the watch in low light.
• Calendar and display controls: The full auto-calendar is programmed to the year 2099, and hand shift moves the analog hands aside so the digital display is easy to read. You can also switch between 12 and 24-hour time and turn the button tone on or off.
• Accuracy and battery life: Timekeeping is rated at ±15 seconds per month, and the battery lasts about 3 years on SR726W x 2 batteries. That gives a stable daily reference with infrequent battery changes.

Who the digital quartz watch is for

The Casio G-Shock GA-2100RC-1A suits men who want a durable watch with a rust-inspired look and practical digital tools. The black and rust colourway with sepia and light blue accents gives it an industrial character, while the carbon and resin build and 200-meter water resistance make it ready for active days. It works well for people who travel, train or spend time outdoors and still want one watch for everyday wear.

• Everyday wear for work and weekends when you need a reliable, hard-wearing watch.
• Travel where world time and alarms help you track different time zones.
• Training sessions that use the stopwatch or countdown timer.
• Swimming, snorkeling and other water sports within the 200-meter rating.
• Outdoor use where shock resistance and a light 51 g build matter.

Less suitable if: you prefer a fully analog watch or a design without digital display functions.

Digital quartz watch specifications

Using and caring for the Casio G-Shock GA-2100RC-1A

The Casio G-Shock GA-2100RC-1A is made for regular wear, and a few simple habits keep the resin band and carbon case in good condition. The 200-meter water resistance allows swimming and snorkeling, but the buttons should not be pressed underwater. Rinse the watch with fresh water after saltwater or heavy sweat, and store it in a dry place when you are not wearing it.

• Rinse the resin band and case with fresh water after contact with saltwater or sweat.
• Keep the watch in a dry place when stored to limit moisture buildup.
• Use the hand shift feature when the analog hands cover the digital display.
• Avoid pressing buttons while underwater, even though the watch is rated to 200 meters.
• Keep the watch away from extreme temperatures, which can affect battery performance.

How to choose the right digital quartz watch

When you choose a digital quartz watch, start with the water resistance and the size on your wrist. The Casio G-Shock GA-2100RC-1A offers 200-meter water resistance and a band that fits wrists from 145 to 215 mm, so it suits active use and a wide range of wrist sizes. Next, check the timekeeping tools: this model provides world time across 31 time zones, a 1/100-second stopwatch, a 24-hour timer and five daily alarms. The carbon and resin case, 51 g weight and black and rust finish are the final points to weigh if you want a light watch with an industrial look.

Frequently asked questions

What is the Casio G-Shock GA-2100RC-1A made of?

The Casio G-Shock GA-2100RC-1A has a carbon and resin case and bezel, a resin band with Carbon Core Guard structure, and mineral glass. The build keeps the watch light at 51 g while adding shock resistance.

What does 200-meter water resistance mean on this watch?

It means the watch is rated for swimming, snorkeling and water sports to 200 meters. It is not designed for diving, and the buttons should not be pressed underwater.

Will the band fit a small or large wrist?

The compatible band size is 145 to 215 mm. That range covers many wrist sizes, and the resin band is designed to sit securely.

How long does the battery last?

The battery lasts approximately 3 years on SR726W x 2 batteries. The double LED light, alarms and world time all run from that power source.

What timekeeping features does the Casio G-Shock GA-2100RC-1A include?

It includes world time for 31 time zones, a 1/100-second stopwatch, a countdown timer, five daily alarms and an hourly time signal. A full auto-calendar runs to the year 2099.

Does the watch have a light for reading in the dark?

Yes, it has a double LED light for the face and digital display. You can set the illumination to 1.5 or 3 seconds, and it includes afterglow.

Can I use the Casio G-Shock GA-2100RC-1A for diving?

No, the watch is rated to 200 meters for swimming and snorkeling but is not intended for diving. Leave the buttons alone while you are in the water.

What warranty comes with the watch?

The Casio G-Shock GA-2100RC-1A comes with a 1-year international warranty. Keep the product information with your purchase records.