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Combining different materials to express new colors

Introducing a new GSTB400 model with the slimmest profile of any watch in the G-STEEL line, which is known for the appealing look of carbon and metal. The bezel features a new green IP finish, adding an original color to the toughness realized by combining different materials.
*Based on a Casio survey as of September 2021.


Green IP bezel

Beautiful original new colors: Green IP bezel

The bezel features a deep and vivid green IP finish that brings out the texture of metal. The new finish exudes maturity and a subtle individual quality.

Mechanical face with a refined look

Mechanical face with a refined look

The dial gives a sense of depth and is combined with the G-STEEL’s iconic dial indicator, together with bridge parts and dimensional index marks. The power-saving module allows for a more opaque dial, which frees up design possibilities.

Slimmest profile G-STEEL yet

Toughness balanced with wearability: Slimmest profile G-STEEL yet

A carbon fibre-reinforced resin case provides shock resistance while reducing the weight, resulting in a case that is just 12.9mm slim. We have downsized the button guards to deliver slim yet ample stainless steel buttons that are easy to feel.

*Image shows the GSTB400-1A.
Carbon Core Guard structure, both strong and light

Carbon Core Guard structure, both strong and light

Offering strength, lightness, and excellent weather resistance, the carbon fibre-reinforced resin case protects the module. Fine resin buffering components are placed between the stainless steel upper and lower bezels to help absorb external shocks.

*Image shows the GSTB400D-1A.
Slim power-saving module

Slim power-saving module

Optimized, high-density mounting of the circuit board structure made it possible to slim the module. A substantial reduction in power consumption was also achieved by reducing the number of watch hands to two and adopting a low-power Bluetooth® system. The ability to solar charge with an opaquer dial freed up the possibilities for the dial design.

*Image shows the GSTB400D-1A.
Metal band with double slide lever for easy band changes

Metal band with double slide lever for easy band changes

*Image shows the GSTB400AD-1A4.
Super Illuminator (high-brightness double LED light) for maintaining watch readability in the dark

Super Illuminator (high-brightness double LED light) for maintaining watch readability in the dark

*Image shows the GSTB400D-1A.
Solar-powered timekeeping with Bluetooth

Solar-powered timekeeping with Bluetooth® for enhanced accuracy and reliability

G-SHOCK Connected

Multiple functions, all at your fingertips FREE

G-SHOCK Connected (smartphone app)

- Time & Place log

Pressing a button on the watch records the current date/time and position on a map within the app. Useful as an activity log.

- Reminder setting

The watch will remind you of up to five upcoming events, which you set within the app.

- Automatic time adjustment (four times a day)

- World time for over 300 cities

- Home time/world time switching

- Countdown timer/alarm setting

- Phone Finder


  • Shock-resistant structure
  • 20-bar water resistance
  • Tough Solar (Solar powered)
  • Smartphone Link
  • Hand shift feature
  • World time (38 cities)
  • 1/100-second stopwatch
  • Countdown timer
  • 5 daily alarms
  • Double LED light (Super Illuminator)
Note: Bluetooth® is a registered trademark or trademark of Bluetooth SIG, Inc.