Casio G-Shock GA-2100 (CasiOak) vs Casio G-Shock GA-B2100

Both watches share the same octagonal CasiOak shape, 200 m water resistance and shock-resistant carbon core, so the choice comes down to power and connectivity. The GA-B2100 adds Tough Solar charging and Bluetooth smartphone link, which means you rarely touch the battery and the clock sets itself. The base GA-2100 is the simpler, lighter-feeling watch and is the one to pick if you want a no-fuss beater. Owners of both praise the slim case and legible analog-digital dial; the main complaints are the 45 mm width and the resin feel.

• Choose the GA-2100 if you want the classic CasiOak look with no charging or app pairing to think about and you don't need solar or Bluetooth.
• Choose the GA-B2100 if you want Tough Solar power and Bluetooth time sync so the watch stays accurate without battery swaps.