CASIO G SHOCK G-STEEL GST-B400-1A

CASIO G SHOCK G-STEEL GST-B400-1A

An ultra-thin module encased in carbon fiber makes for a stylish G-STEEL timepiece with the slimmest profile yet.

Strong, yet lightweight, the carbon core guard structure absorbs external shocks and retains Bluetooth connectivity and solar power functionality even with smaller components and a thinner module. Measuring just 12.9mm from the back of the case to the top of the bezel, the GST-B400 is over a millimeter thinner than its predecessor.

Your choice of four distinctive styles—the simplicity of a silver metal band and silver case; light silver case set against dark resin band; dial in dramatic red vapor deposition finish paired with a black ion-plated bezel; or dial in bold blue vapor deposition finish with black ion-plated bezel and band. With top bezels treated with five different finishes and middle bezels treated with four, these G-STEEL timepieces deliver exceptional metal textures from every angle.

Specs :

Construction & Materials

• Shock-resistant structure — classic G-SHOCK durability.
• Carbon Core Guard case (carbon fiber-reinforced resin) for strength with reduced weight and thickness.
• Case / Bezel material: Resin & Stainless steel (textured metallic finishes).
• Band: Resin strap for comfort and durability.
• Glass: Mineral glass (good scratch resistance).

Dimensions & Weight

• Case size: Approx. 46.6 × 49.6 × 12.9 mm.
• Weight: Approx. 80 g — relatively light for a G-Steel model.

Durability

• Water resistance: 200 meters (20 bar) — suitable for swimming and daily water exposure.
• Shock resistance: Certified G-Shock impact protection.

Power

• Tough Solar: Solar-powered charging means no regular battery changes — charges from sunlight and indoor light.

Connectivity

• Bluetooth® Smartphone Link:
  • Auto time adjustment up to 4×/day.
  • World time (300+ cities).
  • Reminder & time/place log features.
  • Easy setting of alarms, timer, world time, etc.
  • Phone finder function.

Functions

• Analog & digital time display (two hand time + digital).
• World Time: 38 time zones (38 cities + UTC).
• Stopwatch: 1/100-second stopwatch.
• Countdown Timer.
• 5 Daily alarms + hourly time signal.
• Hand shift feature: Moves hands out of the way to view the digital display clearly.
• Double LED light: High-brightness LED for both the analog face and digital display — selectable lighting duration and afterglow for clear visibility in darkness.

Calendar & Timekeeping

• Full auto-calendar (pre-programmed through 2099).
• 12/24-hour format.

Accuracy & Power Saving

• Accuracy: Approx. ±15 seconds per month (without mobile link).
• Battery Life:
  • Approx. 7 months on full charge (normal use).
  • Approx. 18 months in power-saving mode (no light exposure).

Design & Style Highlights

• A slim G-STEEL profile compared with older models — only ~12.9 mm thick.
• Textured finishes on multiple surfaces for a refined metal look.
• Combines classic G-Shock ruggedness with a more refined everyday style suitable for both casual and semi-formal wear.
• Carbon reinforcement and innovative dial design contribute to both strength and reduced power consumption.