Casio G-SHOCK Watch GM-2100C-5AER

Introducing the Casio G-SHOCK GM-2100C-5AER, the version of the legendary GA-2100 that unites tactical toughness with genuine metallic refinement. The octagonal metal case with brushed finish and polished edges catches light from every angle, creating a striking contrast against the khaki sand fabric strap with black resin end pieces. The dial is fully matte black, featuring applied rectangular silver-tone indices and bicolor hands in white and luminescent green that lend a military character to the overall look. The upper-left subdial houses a dedicated day-of-week hand in gold tone, set within a small circular dial marked N, S, E, W. At 4 o'clock a double LCD window displays the secondary time zone and date on a grey background. The octagonal bezel carries engraved white text reading «G-SHOCK», «PROTECTION», «ADJUST», «LIGHT», «MODE» and «START», while «WR 20BAR» and the gold G-SHOCK Casio logo are printed on the dial itself.

At the heart of this watch beats the Casio module 5611, a high-precision analog-digital caliber. The left subdial shows the day of the week via a dedicated hand, while the right LCD alternates between a second time zone and the date. Available functions include world time across 31 time zones and 48 reference cities, a 1/100-second stopwatch with 1-hour capacity, countdown timer, five independent daily alarms, hourly time signal, auto calendar pre-programmed to 2099, daylight saving time toggle and battery saving mode. The MUTE, ALM and SIG indicators visible on the dial confirm the active status of alarms and signal. Neobrite LED illumination provides instant readability of both hands and display in low-light conditions.

The G-SHOCK line was born in 1983 from one Casio engineer's obsession: build an unbreakable watch. After more than 200 destroyed prototypes, the result was the Triple 10 structure: resistance to drops from 10 meters, 10-bar water resistance and 10-year battery life. The GM-2100C carries that indestructible DNA forward through the Carbon Core Guard architecture, surrounding the module with a high-strength resin inner structure inside a metal case, achieving the balance between extreme protection and dress-watch presence. The fabric strap with resin core delivers wrist comfort and abrasion resistance suited to intensive daily wear.

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Technical Specifications

Reference: GM-2100C-5AER
Module/Caliber: 5611
Type: Analog-Digital
Movement: Quartz
Water Resistance: 200 meters (20 BAR)
Shock Resistance: Yes, Carbon Core Guard structure
Case Material: Metal (stainless steel with resin core)
Case Color: Brushed silver with polished edges
Strap Material: Fabric with resin core
Strap Color: Khaki sand with black ends
Dial Color: Matte black
Crystal: Mineral
Illumination: LED (Neobrite on hands and display)
Diameter: 44.4 mm
Dimensions: 44.4 x 49.3 mm
Thickness: 11.8 mm
Weight: 72.0 g
Functions: World time (31 zones, 48 cities), 1/100-sec stopwatch (up to 1 hour), countdown timer, 5 daily alarms, hourly time signal, auto calendar (to 2099), DST toggle, battery saving mode, MUTE / ALM / SIG indicators
Battery: SR726W x 2
Made for: Men

User manual

Download the manual in English (PDF)