CASIO G-Shock GST-B400D-1AJF G-Steel Bluetooth Solar Watch

Items Description

The CASIO G-Shock GST-B400D-1AJF G-Steel Bluetooth Solar Watch is a solar-powered analog-digital timepiece designed for wearers who need the shock resistance and 200-meter water resistance of the G-Shock line in a slimmer stainless steel form. As part of the G-STEEL series, it pairs a resin and stainless steel case with a solid stainless steel band, positioning it between the brand's resin-bodied utility watches and its all-metal premium models.

 

Measuring 46.6 x 49.6 x 12.9 millimeters and weighing 160 grams, the GST-B400D-1AJF represents one of the thinner constructions in this series. The black dial carries analog hands alongside digital sub-displays, and the watch draws power from light through Casio's Tough Solar system rather than a replaceable battery. Bluetooth connectivity links the watch to a smartphone for time correction and settings management.

 

Key Advantages of the CASIO G-Shock GST-B400D-1AJF G-Steel Bluetooth Solar Watch: Slim 12.9mm Stainless Steel Case with Tough Solar and Smartphone Link

 

1. Slim 12.9mm Case Profile

The GST-B400D-1AJF measures 12.9 millimeters from the back of the case to the top of the bezel, a reduction that changes how the watch sits under a shirt cuff and against the wrist. Much of this is achieved through a redesigned module layout that reduces the internal stack height without removing core functions.

 

• Dimensions: 46.6 x 49.6 x 12.9 mm, with a 160 g total weight including the steel band.
• Wearability: The thinner profile reduces the chance of cuff snagging compared with thicker G-Shock models.
• Structural integrity: The slim case retains the shock-resistant structure and 200-meter water resistance rating.

 

2. Tough Solar Charging System

The watch runs on Casio's Tough Solar system, which converts light from both natural and artificial sources into stored energy. There is no user-replaceable battery to swap out, so the watch continues running as long as it receives adequate light exposure, including through a window or under indoor lighting.

 

• Power source: Solar panel integrated into the dial face.
• Charging conditions: Charging occurs under sunlight, fluorescent light, and other common indoor light sources.
• Maintenance: Eliminates the routine battery replacement cycle common to quartz analog watches.

 

3. Bluetooth Smartphone Link

Bluetooth connectivity pairs the GST-B400D-1AJF with a smartphone running the Casio Watches app. The link is used for automatic time adjustment, which keeps the analog hands and digital displays synchronized to the correct time zone when the user travels. Settings such as alarms, world time, and display preferences can be configured from the phone rather than through the watch's buttons.

 

• Auto time correction: The watch syncs to the phone's network time, useful when crossing time zones.
• Remote settings: Alarm, timer, and world time adjustments are made through the app.
• Hand shift: The hand shift feature moves the analog hands out of the way to keep the digital display readable.

 

4. Analog-Digital Display with Hand Shift

The dial combines physical analog hands with digital sub-windows, giving the wearer both a conventional time reading and access to secondary data. The hand shift feature temporarily moves the analog hands aside so the digital display remains unobstructed when the user is reading a stopwatch, timer, or world time entry.

 

• Dual display: Analog hands for at-a-glance time reading, digital windows for additional data.
• Hand shift: Hands move automatically or manually to clear the digital display area.
• Legibility: The black dial provides contrast for the hands and markers.

 

5. Stainless Steel Case and Band Construction

The case and bezel combine resin with stainless steel, and the watch is fitted with a solid stainless steel band secured by a tang buckle. This combination gives the GST-B400D-1AJF a metal-forward appearance while retaining the resin elements that help absorb impact in a shock-resistant design.

 

• Materials: Resin and stainless steel case with bezel, paired with a stainless steel band.
• Finish: Black dial with a steel band that suits both casual and business-casual wear.
• Closure: Tang buckle fastening.

 

6. Shock Resistance and 200-Meter Water Resistance

The GST-B400D-1AJF carries the G-Shock line's shock-resistant structure, which protects the module against impact and vibration. It is also rated to 200 meters of water resistance, a level that supports swimming, showering, and water sports rather than incidental contact with water only.

 

• Shock resistance: Case construction designed to absorb impacts to the module.
• Water resistance: 200-meter rating suitable for swimming and surface water activities.
• Durability context: These ratings match the specifications Casio lists for the GST-B400 series.

 

The GST-B400D-1AJF suits buyers who want the durability ratings of a G-Shock but prefer a thinner case and a stainless steel band over a bulky resin strap. Its combination of solar charging, Bluetooth time correction, and 200-meter water resistance makes it a practical daily wear option for commuters, travelers, and anyone who wants a metal-bodied analog-digital watch that does not require regular battery changes. For those who split their time between office environments and outdoor activity, the slim profile and shock-resistant construction offer a workable middle ground.

Specifications of CASIO G-Shock GST-B400D-1AJF G-Steel Bluetooth Solar Watch

Brand Name	Casio
Model number	GST-B400D-1AJF
Part Number	GST-B400D-1AJF
Case diameter	49.6 millimeters
Case Thickness	12.9 millimeters
Band width	27.3 millimeters
Band Color	Silver
Dial color	Black
Item weight	7.62 Ounces
Movement	Japanese Quartz
Display Type	Analog-Digital

Prev:  Citizen Men's Eco-Drive Promaster Air Nighthawk Watch, Black Leather Strap, Black Dial, Dual Time (Model: BJ7137-07E)     Next: Casio Men's MRW200H-1EV Black Resin Quartz Watch with Black Dial

Specifications
[Brand Name ]	Casio
[Model number ]	GST-B400D-1AJF
[Part Number ]	GST-B400D-1AJF
[Case diameter ]	49.6 millimeters
[Case Thickness ]	12.9 millimeters
[Band width ]	27.3 millimeters
[Band Color ]	Silver
[Dial color ]	Black
[Item weight ]	7.62 Ounces
[ Movement ]	Japanese Quartz
[Display Type ]	Analog-Digital

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