Casio to Release G-STEEL with New Carbon Core Guard Structure

Featuring the Iconic Front Button

March 19, 2020


TOKYO, March 19, 2020 — Casio Computer Co., Ltd. announced today the release of the GST-B300, the latest addition to the G-STEEL line of G-SHOCK shock-resistant watches. The GST-B300 is the first G-STEEL watch with a front button, which adopts a new Carbon Core Guard structure that delivers superior shock resistance by leveraging the lightness and outstanding rigidity of carbon fiber.

For the GST-B300 with front button design, Casio developed a new Carbon Core Guard structure, which protects the module with a carbon case. Highly durable carbon fiber-reinforced resin is added not only to the center case, but also to the front and side button guards, providing even stronger resistance to shocks from above or below, or from any side.

The battery indicator at the 6 o’clock position, designed to evoke a brake disk, shows the remaining battery power by an arrow pointer and a curved red bar, providing visually interesting ways to check the battery.

As for functions, in addition to automatic time adjustment via Bluetooth ® when paired with a dedicated smartphone app, the watch features world time setting for over 300 cities as well as various alarm and countdowin timer settings, all easy to use. It is also equipped with other practical functions such as the Tough Solar, solar charging system developed by Casio, and a high-luminosity full auto double LED light.

GST-B300 Promotion movie


Water Resistance
200 meters
Communication Specifications
Communication Standard
Bluetooth ® low energy
Signal Range
Up to 2 meters (may differ depending on surrounding conditions)
World Time
39 time zones *1 (39 cities + coordinated universal time), daylight saving on/off, auto summer time (DST) switching, home time/world time swapping
  • *1 May be updated when connected to a smartphone.
Measuring capacity: 00'00"000 to 59'59"999 (for the first 60 minutes), 1:00'00"0 to 23:59'59"9 (after 60 minutes); measuring unit: 1/1000 second (for the first 60 minutes), 1/10 second (after 60 minutes); measuring modes: elapsed time, split time
Countdown Timer
Measuring unit: 1/10 second (maximum 24 hours)
5 multi-function alarms (with daily, 1 time, schedule); hourly time signal
Other Features
Mobile Link functions (world time: over 300 cities, automatic time adjustment, easy watch setting, phone finder); hand shift feature; 12/24-hour format; button operation tone on/off; full auto-calendar; battery level indicator; full auto double LED light (Super Illuminator with afterglow: 1.5/3.0 seconds)
Power Source
Tough Solar power system (solar-charging system)
Continuous Operation
About 19 months with the power-saving function *2 ON after full charge
  • *2 Power-saving after a certain period in a dark location
Size of Case
51.0 × 50.0 × 15.5 mm
Total Weight
Approx. 82g
  • The Bluetooth ® word mark and logos are registered trademarks owned by Bluetooth SIG, Inc. and any use of such marks by Casio Computer Co., Ltd. is under license.