The Casio G-SHOCK GMC-B2100ADS-1A is a refined, full-metal take on the octagonal 2100 silhouette, with a fully analog three-subdial layout in stainless steel. The dial is finished in a silvery metallic vapor deposition, framed by three black inset sub-dials that quietly carry the dual-time, stopwatch and day-of-the-week functions. It is one of the more understated entries in the series, with no bright accents — just the play of light across hairline-brushed and mirror-polished surfaces.
The 51.3 × 46.3 mm stainless steel case carries a circular hairline finish across the top of the bezel with mirror polishing along the slopes, framing a 12.4 mm side profile — 0.4 mm thinner than the GM-B2100 that sits below it in the lineup. Casio achieved that slim height by reworking hand positioning and using a more compact retention mechanism, with internal layout solutions borrowed from its OCEANUS and MR-G ranges. The band carries dimpling on the metal links that echoes the texture of the very first G-SHOCK resin band, while a screw-lock crown, mineral glass and 20 bar (200-metre) water resistance complete a build that keeps the shock-resistant structure intact with internal resin buffering between case and bezel.
Power comes from Tough Solar, with the minute hand advancing in 10-second steps so it always lands precisely on the markers. The three sub-dials handle mode and battery indication, dual time / stopwatch / countdown timer / alarm hour and minute, and the day of the week. Bluetooth Smartphone Link via the CASIO WATCHES app takes care of automatic time adjustment, access to approximately 300 world time cities, time and place log and phone finder. On a full charge the watch runs for around five months in normal use, extending to roughly 18 months in the dark with the power-save function on. A high-brightness LED light keeps the dial readable after dark.
Like the rest of the Full Metal line, the GMC-B2100ADS-1A is crafted at Yamagata Casio — the factory where the very first G-SHOCK was made over forty years ago. For anyone drawn to the octagonal 2100 silhouette but looking for something that wears closer to a classic sports chronograph, this all-grey full-metal variant is a quietly serious addition to the range.
Module Number: 5733
Movement Type: Tough Solar (solar-powered quartz)
Precision: ±15 seconds per month (with no mobile link function)
Battery operating time: Approx. 5 months on full charge with normal use; approx. 18 months in total darkness with power-save function on
Weight: 171 g
Water Resistance: 20 bar (200-metre water resistance)
Case Material: Stainless steel
Case Size (Length × Width × Thickness): 51.3 × 46.3 × 12.4 mm
Crystal: Mineral glass
Crown: Screw-lock crown
Band: Stainless steel solid band (fits wrists 150–205 mm)
Clasp: One-touch three-fold clasp
Display: Full analog with silvery metallic vapor-deposited dial and three black inset sub-dials
Backlight: High-brightness LED light
Calendar: Day display
Smartphone Link: Bluetooth wireless linking via CASIO WATCHES app (automatic time adjustment, approximately 300 world time cities, time & place log, phone finder, hand alignment correction)
Dual Time: Sub-dial display with home city time swapping
Stopwatch: 1-second stopwatch (measuring capacity 23:59’59, elapsed time and split time)
Timer: Countdown timer (1 minute to 24 hours)
Alarm: Alarm function via sub-dial
Other features: Shock-resistant structure with internal resin buffering, battery level indicator, made in Japan (Yamagata Casio)
Regular timekeeping: 3 hands (hour, minute hand moves every 10 seconds, second); 3 sub-dials (mode and battery, dual time / stopwatch / countdown timer / alarm hour and minute, day)
