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.

* Slimmest profile as of December 2020

Smartphone Link feature

• Mobile link (Wireless linking using Bluetooth®)

Apps

• CASIO WATCHES

App connectivity feature

• Auto time adjustment
• Easy watch setting
• Approximately 300 world time cities
• Time & place
• Reminder
• Phone finder

World time

• 38 time zones (38 cities + coordinated universal time), city code display, city name display, daylight saving on/off, auto summer time (DST) switching, Home city/World time city swapping
• Stopwatch
• 1/100-second stopwatch
• Measuring capacity: 
• 00'00''00~59'59''99 (for the first 60 minutes)
• 1:00'00~23:59'59 (after 60 minutes)
• Measuring unit: 
• 1/100 second (for the first 60 minutes)
• 1 second (after 60 minutes)
• Measuring modes: Elapsed time, lap/split time

Timer

• Countdown timer
• Measuring unit: 1 second
• Countdown range: 60 minutes
• Countdown start time setting range: 1 second to 60 minutes (1-second increments and 1-minute increments)
• Alarm/hourly time signal
• 5 daily alarms
• Hourly time signal

Light

• Double LED light
• LED light for the face (Super illuminator, selectable illumination duration (1.5 seconds or 3 seconds), afterglow)
• LED backlight for the digital display (Super illuminator, selectable illumination duration (1.5 seconds or 3 seconds), afterglow)

Calendar

• Full auto-calendar (to year 2099)

Mute feature

• Button operation tone on/off

Energy saving feature

• Power Saving (display goes blank to save power when the watch is left in the dark)
• Battery display/alert
• Battery level indicator

Run time

• Approx. battery operating time:
• 7 months on rechargeable battery (operation period with normal use without exposure to light after charge)
• 18 months on rechargeable battery (operation period when stored in total darkness with the power save function on after full charge)

Accuracy

• Accuracy: ±15 seconds per month (with no mobile link function)

Other features

• 12/24-hour format
• Date/month display swapping
• Day display (days of the week selectable in six languages)
• Hand shift feature (Hands move out of the way to provide an unobstructed view of digital display contents.)
• Regular timekeeping:
• Analog: 2 hands (hour, minute (hand moves every 20 seconds)), 1 dial (battery level, mode)
• Digital: Hour, minute, second, pm, month, date, day

Shipping Note: Shipping to Alaska, Hawaii, APO addresses, or PO Boxes is not available for this item.

Warranty: 90 Day Woot Limited Warranty

Optional Asurion Protection Plan: To further protect your purchase, you can buy an Asurion protection plan from Amazon here. Review the FAQs for additional information.