Welcome in the Year of the Snake with a special edition G-STEEL crafted at the intersection of metal and resin. Celebrate 2025 with innovative form and design inspired by the ancient ouroboros.
 
This slim GST-B400 features an ouroboros motif, the ancient auspicious symbol of a serpent eating its own tail, representing infinity and immortality.
 
This special timepiece pairs a silver-colored metal bezel and black watch face with gold-colored accents for a design that takes you smoothly from casual settings to formal occasions and back again.
 
The side buttons and strip across the face from the 3 o’clock to 9 o’clock position add textural appeal with a snake pattern touch that nods to the Year of the Snake. The case back is engraved with a special ouroboros illustration representing infinite possibility.
 
The GST-B400 brings together smaller components and a thinner module to deliver an even slimmer profile, while still offering the Bluetooth connectivity and solar power charging you want for greater convenience and significantly less power consumption. Add to this the watch’s Carbon Core Guard structure, and you have the slimmest G-STEEL yet (as of December 2024), measuring just 12.9 mm from case back to bezel top, over a millimeter slimmer than the GST-B100.
 
Passionate attention to the smallest details — with large, easy-to-press stainless steel buttons, a resin band, and silver metal case featuring different finishes on the top and middle bezels — achieves an elegant, transformative look worthy of the Year of the Snake.
 
Case size (length x width x thickness) 46.6×49.6×12.9 mm
Weight 86 g
Case/bezel material Carbon steel/stainless steel
Strap material Resin band
Structure Shock-resistant structure (shockproof)
200M waterproof
Power supply/battery life Tough Solar (solar charging system)
Mobile phone linkage function (functional linkage with compatible mobile phones via Bluetooth communication)
Application Compatible with "Casio watches"
Application linkage function
Automatic time correction
Easy clock setting
World time about 300 cities
Time and place
Mobile phone search
Glass Inorganic glass
Adjustable size of strap 145-215 mm
World time: 38 cities around the world (38 time zones, automatic daylight saving time setting function) + UTC (Coordinated Universal Time) time display, home time city switching function
Stopwatch (1/100 second (within 1 hour) / 1 second (over 1 hour), 24-hour meter, with lap/split)
Timer (setting unit: 1 second, maximum setting: 60 minutes, measured in 1 second increments)
5 time alarms/time signals
Dual LED light:
Dial LED light (with super illuminator, afterglow function, afterglow time switching (1.5 seconds/3 seconds)),
LED backlight of LCD part (with super illuminator, afterglow function, afterglow time switching (1.5 seconds/3 seconds))
LED: White
Full auto calendar
Operation sound ON/OFF switching function
Power saving function (turns off the display after a certain time in a dark place to save power)
Battery level display/warning
Accuracy
*If not connected to a smartphone, it will operate with normal quartz accuracy (average monthly difference ±15 seconds).
Hand retraction function (if the hand overlaps with the LCD screen and is difficult to see, you can temporarily withdraw the hand from above the LCD screen.)
12/24 hour display switching
Date display (month/day display interchangeable)
Week display (switchable between 6 languages: English, Spanish, French, German, Italian and Russian)