G-Shock GMAS2100: The Ultimate Compact CasiOak for Every Wrist -

The Casio GA2100 series has become an enthusiast favorite with its tried and tested G-Shock durability and its distinct design. It’s earned the nickname the “CasiOak” based on its similarities to the iconic AP Royal Oak with its octagonal shape and integrated bracelet. However, at 45mm wide and 12mm thick, the fit might be a barrier for some, especially those with slimmer wrists. Enter the GMAS2100, boasting a smaller case size of just under 43mm and a thickness of around 11mm.

The GMAS2100 is sold by Casio as the women’s model of the popular CasiOak, but make no mistake – this watch is perfectly unisex in its dimensions, and available in some unique colorways. We had the GMAS2100 on the wrist for a week and are eager to share our thoughts on this reasonably sized offering from Casio.

Table Of Contents

The Case
The Dial
The Functionality
The Lume
The Band
The Verdict
The Specs

The Case

Colloquially known as the “Mini CasiOak”, the GMAS2100 is made from a lightweight and shock-resistant resin with carbon fiber embedded throughout its structure for additional strength and durability. Offering a comfortably slender profile while retaining the rugged G-Shock protection the brand is famous for, it strikes a delicate balance between durability and effortless wearability. The watch wears agreeably on my 6.6″ wrist with its 42.9mm width and 11.2mm thickness and weighs in at just 41g.

The model we have in hand for this review is the GMAS2100GA-7A, a delightful off-white colorway with teal accents that takes a sophisticated spin on the color palette of the 1990s, and would look right at home in the lineup of Hodinkee x John Mayer DW6900 collaborations.

The Dial

The GMAS2100 dial features a step-down design with hour markers highlighted by the accent color of the watch, teal for our GMAS2100GA-7A, along the edge of the chapter ring. The accent color is again reflected in the text on the dial, and on the hands across the watch. The majority of the analog hands are finished in a polished finish with applied lume. At 9 o’clock is a 180-degree analog day of the week complication.

Spanning the bottom right quadrant of the dial is the digital display which houses most of the watch’s functionality. This model features a standard LCD display, but there are models that feature a negative display as well.

The Functionality

The GMAS2100 features a handful of functionality that makes it a perfect everyday or travel companion. The home screen sets to either the digital time or the month and date to complement the analog time shown by the hands. Cycling through the modes, you’ll find a world timer, a stopwatch, a timer, and alarm functions. It’s so entertaining changing your home timezone to another to watch the analog hands sweep and set to your new location.

The Lume

Lume is featured prominently on the hour and minute hands, but in true Casio fashion, the backlight is where the fun is. The light function shoots a beam of white light between 4 and 5 o’clock, illuminating the LCD screen and reflecting off the polished analog hands. The duration of the light can be changed in the watch’s settings, from the standard 1.5 seconds to 3 seconds.

The Band

The band is comfortable and light as one might expect from Casio. Integrated into the watchhead, it features a subtle and comfortable taper down to a color-matched buckle. I was surprised to find that the strap comes with quick-release spring bars should you decide a NATO or other strap would fit the GMAS2100 better.

The Verdict

I’ve been intrigued by the CasiOak since it took the world by storm in 2019, however looking at the specs I knew it would wear far too bulky for my tastes. After learning about the GMAS2100, it was on my shortlist for an everyday digital grab-and-go watch and it does not disappoint in that regard. It’s not just for slim wristers either. I believe this 42.9mm case wears great on all wrists, and the GMAS2100 comes in some interesting monochromatic and pastel colorways that aren’t offered on its bigger brother if that type of aesthetic is for you.