G-SHOCK GA-100-1A4ER

The GA-100-1A4 brings a commanding, industrial presence to the wrists of those who demand absolute structural resilience. Dominated by a massive 55 mm case construction that sits 16.9 mm high, this analog-digital hybrid is engineered for high-impact environments, featuring both G-SHOCK’s legendary shock resistance and a specialized magnetic-resistant shielding. Despite its oversized, armor-like aesthetic and rugged resin bezel, the watch weighs a surprisingly agile 70 grams. The exterior layout is defined by extra-large, textured buttons with a checkered anti-slip finish, ensuring certain and instantaneous operation even when wearing heavy gloves or facing wet conditions.

The face design emphasizes layered, three-dimensional depth, combining traditional analog indicators with high-contrast digital utility. At its center rests a prominent analog dial that serves as a dedicated velocity indicator, framed seamlessly by two distinct digital LCD windows. This configuration powers a hyper-precise 1/1000-second stopwatch capable of measuring split times, lap times, and calculating real-time average speeds over input distances. Outfitted with an amber LED light that activates automatically with a flick of the wrist, the module also supports 29 world time zones, 5 daily alarms with a snooze function, a 24-hour countdown timer, and full 200-metre water resistance for deep aquatic utility.

Basic Information

Reference: GA-100-1A4
Collection: G-SHOCK G-Classic Series
Case dimensions (L × W × H): 55 × 51.2 × 16.9 mm
Weight: 70 g
Case and bezel material: Resin
Water resistance: 20 bar (200 metres)
Construction: Shock Resistant, Magnetic Resistant

Movement & Features

Module type: Analog-Digital Quartz (Module 5081)
Battery life: Approx. 2 years on CR1220
Stopwatch: 1/1000-second; measuring capacity 99:59’59.999”; elapsed, lap, and split times; speed and distance calculations
Timer: Countdown timer, 1-second increments, 24-hour range, auto-repeat
Alarm: 5 daily alarms (1 with snooze), hourly time signal
Calendar: Full auto-calendar (to year 2099)
Accuracy: ±15 seconds per month

Exterior

Glass: Mineral glass
Band: Resin band
Compatible band size: 145 to 215 mm
Illumination: Auto LED light with selectable illumination duration (1.5 or 3 seconds) and afterglow

Display

Layout: Three-dial face design (1 analog speed dial, 2 digital LCD displays)
Colourway: Matte black base with deep red dial accents and white hands
Light colour: Amber LED