CASIO G-SHOCK GA-B2100BEG-1ADR 2100 SERIES TOUGH SOLAR BLUETOOTH ANALOG-DIGITAL BLACK ELECTRO GREEN WATCH

The GA-B2100BEG-1ADR is the Black and Electro Green colourway on G-Shock's most iconic modern silhouette — the octagonal 2100 Series, universally recognised for its slim profile and clean lines. At 11.9mm thin and 52 grams, this is one of the slimmest, lightest G-Shocks ever made — thinner than the GA-B010BEG (15.2mm), thinner than the GBD-200 (15mm), and thinner than most analogue dress watches that lack any of this watch's toughness. The electro green LCD accents and "TOUGH SOLAR" / "Bluetooth" text glow against the matte black dial, adding the same tech-forward energy as the GA-B010BEG but in a dramatically more compact, more wearable, more everyday-suited package.

Module 5689 combines Tough Solar power (no battery changes, approximately 7 months on a full charge), Bluetooth smartphone link via the CASIO WATCHES app, Carbon Core Guard structure for enhanced shock protection, hand shift, and a double LED Super Illuminator that lights both the analog face and the digital display independently. The carbon and bio-based resin case delivers the 2100 Series' signature octagonal geometry with reduced environmental impact. World time covers 38 cities with auto DST switching, the 1/100-second stopwatch includes lap and split modes, and app-configurable reminders can push alerts to the watch for events and tasks. No step counter on this model — if you want step tracking in the BEG colourway, the GA-B010BEG is the option. What you get here instead is the slimmest profile, the longest solar run time, and the most universally wearable silhouette in the G-Shock range. 200-metre water resistance, Neobrite hands, and a 145–215mm band.

At a Glance

Why You'll Love It

• At 11.9mm thin and 52 grams, this is one of the slimmest and lightest G-Shocks available — it slides under shirt cuffs, sits flat against the wrist, and wears more like a fashion watch than a tool watch. The octagonal silhouette is the reason the 2100 Series became a global phenomenon.
• Tough Solar eliminates battery replacements entirely. Approximately 7 months of operation on a full charge (normal use) or 18 months with power save — longer than the GA-B010BEG's 5/26 months. Charge from any light source.
• Carbon Core Guard protects the module inside a carbon fibre reinforced case — a structural upgrade the GA-B010 doesn't have. It's the reason the 2100 Series achieves G-Shock toughness at 11.9mm thin.
• The electro green LCD accents are subtler on the 2100 silhouette than on the larger GA-B010 — "TOUGH SOLAR", "Bluetooth", and the digital display glow green against the black dial, adding tech personality without overwhelming the clean lines.
• Bluetooth auto time sync keeps the watch accurate without any user input — connect once to the CASIO WATCHES app and the time stays perfect.
• The octagonal bezel shape is the most fashion-crossover G-Shock design — it's been adopted by streetwear, menswear, and even suited contexts that traditionally rejected G-Shock's chunky round silhouettes.

Perfect For

Key Features

• Octagonal 2100 Series silhouette at 11.9mm thin — The signature G-Shock design that broke the mould — an octagonal bezel in the slimmest G-Shock profile category. At 52 grams it's lighter than the GA-B010 (57g), the GBD-200 (58g), and most traditional G-Shocks (60–70g). The slim profile is what makes this the G-Shock that works with everything.
• Tough Solar — no battery replacement — Solar-rechargeable cell with approximately 7 months of normal operation on a full charge. Power save mode extends to approximately 18 months. Battery level indicator on the dial subdial at 9 o'clock.
• Carbon Core Guard structure — A carbon fibre reinforced case surrounds the module, providing G-Shock-level shock protection inside the ultra-slim 11.9mm profile. This is the structural engineering that makes the 2100 thin without being fragile.
• Bluetooth smartphone link — Auto time sync, approximately 300 world time cities, app-configurable reminders, phone finder, and easy watch settings via the CASIO WATCHES app. Note: no smart notifications and no step counter on this model.
• Hand shift feature — Analog hands retract when accessing digital functions, clearing the LCD at 6 o'clock. Essential for readability on an analog-digital at this size.
• Double LED Super Illuminator — Separate LEDs for the analog face and digital display, with selectable duration (1.5s or 3s) and afterglow. White light.

Technical Specifications

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Frequently Asked Questions

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