Is the green GA-B2100 the same watch as the black one?

Yes. Both are GA-B2100 models with the same case, module, solar charging and Bluetooth. Only the case and band color differ.

Which color holds up better over time?

Black resin hides scuffs and fading better. Green resin can lighten with long sun exposure, so the black model looks newer longer.

Does either model need a battery change?

No. Both use Tough Solar, so the rechargeable cell is charged by light. Casio rates reserve runtime in months when kept in the dark, not a swap schedule.

Can I swim and shower with either one?

Yes. Both are rated to 200 m, which covers swimming, snorkeling and showering. Neither is a dive computer.

Is the step up to a higher G-Shock worth it?

Only if you want features these lack, such as sapphire crystal, a larger display or a metal case. For basic tough solar timekeeping, the GA-B2100 pair covers it.

Casio G-Shock GA-B2100 vs Casio G-Shock GA-B2100

These are the same watch: the GA-B2100-1A and GA-B2100-3ADR share the 48.5 × 45.4 × 11.9 mm carbon-core case, Tough Solar, Bluetooth link and 200 m rating. The only real difference is color, black versus green. Buy whichever color you will actually wear; there is no functional reason to pick one over the other. Owners of the 2100 line praise the slim case and legible analog-digital dial, and the common complaints are the mineral crystal and the small LCD.

Choose the GA-B2100-1A if you want the black case and band that goes with everything and hides scratches better.
Choose the GA-B2100-3ADR if you want the green case and band and a black dial for a sportier look.

Prices

Casio G-Shock GA-B2100: $134.99 at Amazon (last seen Nov 9)
Casio G-Shock GA-B2100: $134.99 at Amazon (last seen Nov 8)
Difference: both cost the same at the latest prices (Nov 8 and Nov 9)

Casio G-Shock 2100 Series GA-B2100-1A Men's Watch

What separates them

	Casio G-Shock GA-B2100	Casio G-Shock GA-B2100
Colorway	Black case and band, black dial	Green case and band, black dial
Movement and power	Tough Solar with Bluetooth smartphone link	Tough Solar with Bluetooth smartphone link
Case and size	Carbon core guard, 48.5 × 45.4 × 11.9 mm	Carbon core guard, 48.5 × 45.4 × 11.9 mm
Water resistance	200 m (20 bar)	200 m (20 bar)
Weight	About 52 g	52 g
Crystal	Mineral	Mineral
Scratch visibility	Black resin hides scuffs and fading well	Green resin shows scuffs and sun fading more

Specs compared

Spec	Casio G-Shock GA-B2100	Casio G-Shock GA-B2100
Water resistance	20-bar water resistance	200-meter water resistance
World time	38 cities	38 time zones (38 cities + coordinated universa…
Stopwatch	1/100-second stopwatch	1/100-second stopwatch
Alarms	5 daily alarms	5 daily alarms
Case material	Carbon	Carbon / Resin
Power source	Tough Solar (solar powered)	—
Connectivity	Smartphone Link	—
Light	Double LED light (Super Illuminator)	—
Diameter	48.5 × 45.4mm	—
Thickness	11.9 mm.	—
Crystal	Mineral	—
Strap	Resin	—

Show all 19 specs

Spec	Casio G-Shock GA-B2100	Casio G-Shock GA-B2100
Case size	—	48.5 × 45.4 × 11.9 mm
Weight	—	52g
Battery operating time	—	7 months on rechargeable battery
Power save runtime	—	18 months on rechargeable battery
Accuracy	—	±15 seconds per month (with no mobile link func…
Countdown timer	—	60 minutes
Band material	—	Resin Band

Casio G-Shock GA-B2100 vs Casio G-Shock GA-B2100

Prices

Casio G-Shock GA-B2100 vs Casio G-Shock GA-B2100

Prices