G-Shock Updates the Compact "CasiOak" in Monochromatic Black and Brown

Earlier this fall, Casio-owned G-Shock added two monochromatic versions to its compact CasiOak lineup, giving the famed octagonal design a new look. The GMA-P2110B-1A comes in black, while the GMA-P2110B-5A does the same in brown. Both combine a resin exterior with a metallic bezel ring, adding a little shine to an otherwise muted watch.

The pair belongs to the smaller-sized GMA-P2110 family, which Casio debuted in 2025 and markets within its women’s collection. At 40.5mm wide, these models are substantially narrower than the original GA-2100, though they retain the analog-digital display, shock resistance, and 200-meter water-resistance rating associated with the series.

The story of G-Shock’s 2100 series, aka the "CasiOak," began with the GA-2100 in 2019. Its octagonal bezel and relatively slim profile gave G-Shock a recognizable alternative to its square digital watches. The design quickly became a fan favorite, earning its nickname as a nod to the iconic Audemars Piguet Royal Oak, just — well — for Casio.

The design has since expanded into a growing range of sizes, materials, and colors. The GM-2100 brought a metal bezel to the collection in 2021, the same year the GMA-S2100 introduced a smaller case. The even more compact GMA-P2100 followed in 2024 with turquoise, pink, and white monochromatic options. 

More recently, the GMA-P2110 introduced a separate bezel ring and a simpler face, with initial versions in black, beige pink, and white arriving in 2025. This year has also brought the GA-2100CM camouflage models, which use a patterned case and strap to give the larger CasiOak a very different look. The latest GMA-P2110B is a bit quieter, carrying its black or brown palette across the case, dial, and band.

The GMA-P2110B case measures 40.5mm wide, 46mm long, and 11.3mm thick, with a total weight of 37 grams. For comparison, the standard GA-2100 measures 45.4mm wide, 48.5mm long, and 11.8mm thick, and weighs 51 grams. The difference is most noticeable in width, making the GMA-P2110B worth considering for anyone who likes the CasiOak shape but finds the original a bit large. Its shorter strap is sized for wrists measuring 145mm to 190mm.

The bezel’s construction is the main design story. A separate ring with a vapor-deposited metallic finish frames the upper resin bezel, catching light along its inner and outer edges. It follows the familiar eight-sided outline while adding a reflective border against the matte surfaces. The effect is restrained enough to suit the monochromatic colors without disappearing into them.

Key components in the bezel and strap use bio-based resin, which Casio says is produced using renewable organic resources and is expected to help reduce environmental impact. The material has also appeared on earlier compact CasiOaks, including the GMA-P2100, and this year’s camouflage-themed GA-2100CM. Both new models have shock-resistant construction, a mineral crystal, and 200 meters of water resistance.

The dial continues the color of the exterior, with sharply shaped, three-dimensional bar indexes and two central hands for the hours and minutes. The GMA-P2110 family also leaves out the bezel logos and mode-indicator engravings found on more heavily marked G-Shocks, giving the octagonal frame a cleaner appearance than the original iteration.

Black is a classic choice for this sort of subdued G-Shock, bringing the case, strap, and face close together visually. Brown is the less expected option, offering a warmer look, though earth tones are familiar territory for G-Shock—the GBD-800UC-5 and GA-700UC-5A are both currently offered by the brand. The two downsized CasiOaks share their layout and functions, so the choice comes down largely to color.

Inside is Casio’s Module 5730, a battery-powered quartz movement with the analog-digital timekeeping that’s standard to G-Shocks at this price point. Accuracy is rated at ±15 seconds per month, while a single CR1025 battery provides approximately three years of operation.

Functions include world time covering 48 cities across 31 time zones, a 1/100-second stopwatch, a 24-hour countdown timer, and five daily alarms. A full automatic calendar runs through 2099, while the hand-shift function moves the hands aside when they obstruct the digital display. The double LED Super Illuminator lights the dial and digital screen separately.

The G-Shock GMA-P2110B-1A in black and GMA-P2110B-5A in brown are priced at $145 each. 

More info on the G-Shock website.