The octagon that started a movement—now solar-powered and smarter.

Casio's GA-B2100 (the "CasiOak" to the obsessed) brought that Royal Oak aesthetic to G-Shock toughness—and this green colorway takes it from subtle to statement. Solar charging means you'll never replace a battery. Smartphone link means it auto-syncs time. And the Carbon Core Guard structure means it's still absurdly tough despite the slim 11.9mm profile.

Why the GA-B2100 is having a moment:

• That octagonal bezel everyone's chasing (AP homage without the $30K price tag)
• Slimmest analog G-Shock at 11.9mm (fits under a shirt cuff—barely)
• Carbon Core Guard structure (lighter, thinner, just as indestructible)
• Tough Solar charging (sunlight powers it—no battery changes, ever)
• Bluetooth smartphone link (auto time-sync across time zones)

This colorway: Forest green case with pops of color on the dial. Bold enough to be deliberate, muted enough to work with earth tones, military fits, or streetwear. The kind of watch that gets noticed without screaming for attention.

What makes the CasiOak different from every other G-Shock: It's thin. Seriously—11.9mm is shockingly slim for a G-Shock (most are 15-18mm thick). It actually fits under long sleeves and doesn't look like tactical gear. The octagonal bezel gives it that luxury watch silhouette, but it's still a G-Shock underneath—200m water resistant, shock resistant, and built to survive whatever you throw at it.

Tech that actually matters:

• Tough Solar charging (light = power, indefinitely)
• Bluetooth smartphone link (auto time sync, world time updates)
• 200-meter water resistance (swim, surf, shower, forget about it)
• World time (31 time zones)
• 5 daily alarms + stopwatch + timer
• LED backlight (readable in the dark)
• Shock resistant (Carbon Core Guard structure)

Fit & Feel: 48.5mm case wears closer to 45mm due to the slim profile and integrated strap design. If you have a 6.5"-7.5" wrist, this is the sweet spot. Smaller than that, it'll wear large (but still doable). Bigger than that, it might look too refined (which could be the point). The resin strap is comfortable and low-profile—no thick rubber slab like older G-Shocks.

Weight: 52 grams. For reference, that's lighter than an Apple Watch. You forget you're wearing it.

Style versatility: This is the G-Shock you can actually wear with a button-down. Jeans and boots? Yes. Gym gear? Still works. Tactical pants and tee? Absolutely. The slim case and octagonal design elevate it beyond "sports watch"—it reads more like a modern timepiece that happens to be indestructible.

Condition: Brand new in original G-Shock packaging. Full warranty, manual, all original materials.

Ships same or next day from Florida.

Case size (L× W× H):  48.5 × 45.4 × 11.9 mm
Weight: 52 g
Case and bezel material: Carbon / Resin　
Resin Band
Shock Resistant
Carbon Core Guard structure
200-meter water resistance
Power supply and battery life:  Tough Solar (Solar powered)