Casio G-Shock GA-2100AS-5A Sand Beige Bio-Based Resin Men's Watch

The Casio G-Shock GA-2100AS-5A is a sand beige analog-digital men's watch built for everyday wear and outdoor use. It pairs a bio-based resin case and strap with G-Shock shock resistance, 200-meter water resistance and a slim 51-gram build, so it suits men who want a tough watch that stays comfortable on the wrist.

Part of the Oasis Series, this Casio G-Shock GA-2100AS-5A men's watch uses Carbon Core Guard construction to keep the case rigid while holding weight at 51 grams. The dial combines analog hands with a digital display and blue-green accents, protected by mineral glass. World Time covers 48 cities across 31 time zones, and the watch also provides a 1/100-second stopwatch, a countdown timer up to 24 hours, five daily alarms with snooze, a double LED Super Illuminator and a full auto calendar to 2099. The battery is expected to last about three years.

Key features and benefits of the Casio G-Shock GA-2100AS-5A

• Carbon Core Guard structure: The case uses carbon-fiber reinforced resin for a rigid frame that stays light on the wrist. This helps the watch keep its slim profile while supporting G-Shock durability.
• 200-meter water resistance: The case is rated to withstand pressure equivalent to 200 meters depth. That makes the watch suitable for swimming, snorkeling and recreational diving.
• Shock-resistant construction: The module sits suspended inside the case to absorb knocks. Everyday bumps and drops are less likely to disturb timekeeping.
• Bio-based resin case and strap: The material comes partly from renewable organic resources rather than only petroleum-based plastic. It feels soft against the skin and lowers the environmental impact of the watch.
• Analog-digital display with blue-green accents: Hands and an LCD work together to show time and functions, while the blue-green details aid visibility. Mineral glass covers the dial and helps protect it from everyday scratches.
• World Time for 48 cities and 31 time zones: You can check the time in major cities around the world without changing the main setting. It is handy for travel and for coordinating with people in other time zones.
• 1/100-second stopwatch: The stopwatch measures elapsed time to a hundredth of a second. It supports sports timing and interval training.
• Countdown timer up to 24 hours: The timer can count down from one minute to 24 hours. Use it for cooking, parking limits or workout intervals.
• Five daily alarms with snooze: Five separate alarms can cover wake-up, reminders and appointments. The snooze function gives a short repeat when needed.
• Double LED Super Illuminator: Two high-brightness LEDs light the analog and digital sections independently. The face stays readable in complete darkness.
• Hand Shift feature: A button press moves the hour and minute hands away from the digital display. This gives a clear view of digital readouts when the hands would cover them.
• Full auto calendar to 2099: The calendar adjusts for month lengths and leap years through 2099. You do not need to correct the date manually.

Who the Men's Watch is for

The Casio G-Shock GA-2100AS-5A suits men who want one watch for casual wear, travel and active days. The sand beige tone works with streetwear and relaxed outfits, while the 200-meter water resistance and shock resistance make the watch useful for sports, hiking and time near water. World Time and the alarms help frequent flyers and remote workers keep schedules straight.

• Daily commuting and office wear with a casual dress code
• Weekend hiking, cycling or water sports
• International travel across several time zones
• Gym sessions and interval training with the stopwatch and timer
• Outdoor festivals or events where a rugged, legible watch helps

Less suitable if: you prefer a metal bracelet or a classic leather strap for formal business attire.

Men's Watch specifications

Using and caring for the Casio G-Shock GA-2100AS-5A

The bio-based resin strap can be cleaned with mild soap and water. Avoid solvents and abrasive cleaners that could degrade the material. After salt water or chlorine, rinse the Casio G-Shock GA-2100AS-5A in fresh water and dry it with a soft cloth. The mineral glass resists scratches but can chip on sharp impact, so store the watch apart from hard objects. Use Hand Shift when the analog hands cover the digital display, and replace the battery at an authorized service center to help maintain water resistance.

• Rinse with fresh water after swimming in the sea or a pool
• Clean the strap with lukewarm soapy water and a soft brush
• Avoid extreme temperature changes below -10°C or above 60°C
• Check strap fit regularly because resin may stretch slightly over time
• Use the light button to activate the auto-light setting when configured

How to choose the right Men's Watch

When choosing a daily sports watch, look at case material, water resistance, weight and function set. The Casio G-Shock GA-2100AS-5A uses bio-based resin for a lighter feel than metal or traditional resin. Its 200-meter rating goes beyond the 100-meter minimum often used for recreational swimming. At 51 grams, it is light for a G-Shock, which can reduce wrist fatigue. World Time, stopwatch, timer, alarms and illumination cover travel and training needs without adding rarely used sensors.

Frequently asked questions

What is the Casio G-Shock GA-2100AS-5A made of?

The case and strap are made of bio-based resin, a material partly derived from renewable organic resources. The watch also uses Carbon Core Guard construction and a mineral glass crystal.

How water resistant is this men's watch?

The Casio G-Shock GA-2100AS-5A has 200-meter water resistance, so it is suitable for swimming, snorkeling and recreational diving. It is not rated for saturation diving or high-velocity water sports.

Does the watch have a backlight?

Yes. A double LED Super Illuminator lights the analog and digital sections independently, which keeps the face readable in complete darkness.

Can I use the stopwatch for interval training?

The 1/100-second stopwatch measures elapsed time precisely and can record split times. It works for interval training, but the watch does not have a dedicated interval program.

What comes in the box with the Casio G-Shock GA-2100AS-5A?

Included with the Casio G-Shock GA-2100AS-5A are the watch unit, a pre-attached bio-based resin strap and the manufacturer's instruction manual. No extra straps or charging cable are included because the watch uses a battery.

How long does the battery last?

The battery lasts about three years under normal use. Frequent use of the backlight or alarms may shorten that time slightly.

Is the strap replaceable?

The strap uses standard spring bars, so a 20 mm strap can replace it. The original bio-based resin strap is made to match the case color and material.

Who is the Casio G-Shock GA-2100AS-5A for?

It suits men who want a lightweight watch for casual wear, travel, sports and outdoor use. The sand beige color, 200-meter water resistance and World Time functions support those activities.