■ Product Overview
The CASIO G-SHOCK GA-2100-5ADR is a beige analog-digital quartz watch featuring a black dial, an octagonal bezel, Carbon Core Guard construction, shock resistance, and 200-meter water resistance.
Its octagonal design is commonly nicknamed “CasiOak” by watch enthusiasts. “CasiOak” is an unofficial nickname and is not an official CASIO model or series name.
Model Number: GA-2100-5ADR
Base Model: GA-2100-5A
Condition: New
■ Key Features
• Distinctive octagonal bezel design
• Carbon Core Guard structure combining carbon and resin
• G-SHOCK shock-resistant construction
• 200-meter / 20-bar water resistance
• Analog and digital time display
• Double LED illumination for the dial and digital display
• Hand Shift function for improved digital display visibility
• World time covering 31 time zones and 48 cities
• 1/100-second stopwatch
• 24-hour countdown timer
• Five daily alarms and hourly time signal
• Full auto-calendar through 2099
■ Specifications
• Brand: CASIO
• Series: G-SHOCK GA-2100 Series
• Model Number: GA-2100-5ADR
• Display Type: Analog-Digital
• Movement: Battery-Powered Quartz
• Case and Band Color: Beige
• Dial Color: Black
• Case Size: Approx. 48.5 × 45.4 × 11.8 mm
(Length × Width × Thickness)
• Weight: Approx. 51 g
• Case / Bezel Material: Carbon / Resin
• Band Material: Resin
• Glass: Mineral Glass
• Compatible Wrist Size: Approx. 145–215 mm
• Construction: Shock Resistant / Carbon Core Guard
• Water Resistance: 200 meters / 20 bar
• Accuracy: ±15 seconds per month
• Battery: SR726W × 2
• Estimated Battery Life: Approx. 3 years
■ Main Functions
• World Time: 31 time zones covering 48 cities plus Coordinated Universal Time
• Daylight Saving Time on/off
• Home city and world time city swapping
• Stopwatch: 1/100-second measurement for the first 60 minutes and 1-second measurement thereafter
• Stopwatch Capacity: Up to 24 hours
• Stopwatch Modes: Elapsed time, split time, and first/second-place times
• Countdown Timer: 1-second measuring unit with a maximum range of 24 hours
• Alarm: Five daily alarms and hourly time signal
• Lighting: White LED light for the dial and white LED backlight for the digital display
• Selectable LED Duration: 1.5 or 3 seconds with afterglow
• Hand Shift Function
• Button Operation Tone On/Off
• 12/24-Hour Time Format
• Full Auto-Calendar Through 2099
■ Package Contents
• 1 × CASIO G-SHOCK GA-2100-5ADR Watch
Packaging, instruction manuals, warranty documents, and other included materials may vary depending on the distributor, region, production period, or arrival lot. Please confirm the exact contents shown in the listing images.
■ Important Notes
• “CasiOak” is an unofficial nickname used by watch enthusiasts and is not an official CASIO product or series name.
• This is a battery-powered quartz model. It does not support Tough Solar charging, Bluetooth, or smartphone linking.
• GA-2100-5ADR is a regional model designation corresponding to the GA-2100-5A.
• The stated battery life is an estimate and may vary depending on usage and operating conditions.
• Avoid operating the buttons while the watch is submerged or wet unless specifically permitted by the manufacturer’s instructions.
• Water resistance is not permanent and may decrease due to aging, impact, or deterioration of seals.
• Packaging and document languages may vary. International warranty service outside the original sales region is not guaranteed.