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Casio G-Shock 2100 Series 45.4mm Ref:GA-2100-1A

Casio G-Shock 2100 Series 45.4mm

Reference: GA-2100-1A

★★★★★
★★★★★
4.5
2 ratings 2 reviews
The Casio G-Shock 2100 Series 45.4mm in black is a digital/casual watch released under the G-SHOCK collection. In terms of construction this version features a 45.4mm carbon and resin case paired with a resin band and mineral crystal. The movement is an quartz Casio reference 5611.

Essentials

Collection
Year launched
2020
Watch style
Crystal
Mineral
Materials case
Carbon, Resin
Materials band
Resin
Water resistance
200 m

Visuals

Case shape
Round
Case diameter
45.4 mm
Case height
11.8 mm
Lug width
26.1 mm
Lug to lug
48.5 mm
Weight
51 g
Colors case
Black
Colors dial
Black
Colors band
Black

Movement

Caliber
Casio 5611
Type
Quartz
design
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0
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1
1
movement
0
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0
1
1
band
0
0
0
2
0
legibility
0
0
2
0
0
value
0
0
0
0
2
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Variations

Brand - Casio

From its humble beginnings as a calculator manufacturer, Casio quickly diversified its offerings to include watches, becoming synonymous with innovation and reliability. One of its most notable achievements came in 1974 with the introduction of the Casiotron, one of the world's first digital watches, which revolutionized the way people perceive timepieces. Casio continued to push boundaries with the release of the iconic G-Shock line in 1983, renowned for its ruggedness and durability, making it a favorite among adventurers and athletes worldwide. Additionally, Casio has made significant strides in the realm of smartwatches with its Pro Trek and Edifice series, offering cutting-edge features and functionalities while maintaining its reputation for quality and precision. With a commitment to innovation and excellence, Casio remains a leader in the watch industry, catering to a diverse range of consumers with its extensive lineup of timepieces.

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Reviews

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media-libraryquJboC Andrei wrist 6.50"/16.50cm
★★★★★
★★★★★
April 9, 2024

I have the full-black version and it looks like it means business. Joking aside it's a great stealthy-looking sports watch. Also, I got the watch as a gift from my wife so if you are looking to gift this, yeah, go ahead, I think any watch lover would love it in the collection.

The size is perfect for me, it doesn’t look chunky even though it's quite large and the band goes quite sharply downwards and not extending the effective “lug to lug” which helps a lot for smallish wrists.

The build quality is where I have some issues with it. After about 3 years of semi-regular wear, the outer shell has started to warp and get a bit loose. It's not as tight around the watch head as it was when new.

This is something that happened with an older G-Shock that I have as well. I’m not sure how common this issue is but it's something I noticed. The watch still holds together very well so it's not falling apart or anything but it is quite annoying.

Another issue I have with the watch is the lack of lume on the hour makers. I think it would have helped with legibility. Sure there is the usual G-Shock LED light but since there is some lume on the hands why not add on the markers as well?

Some anti-reflective coating would have been nice since at least in the full black version the dial is quite hard to see if light hits the dial. On other color options, it doesn't seem to be as bad. My wife’s GMA in the pink color scheme doesn’t have this issue.

Even though I mostly complained about the watch here, I still think it's a great watch for the money and also there are quite a few mod kits out there to change the look of it, cases, bracelets, and whatnot if you are into modding.

media-libraryhfgXqQ Urszuly Patrik wrist 7.00"/17.78cm
★★★★★
★★★★★
May 8, 2025

The Casioak. The only hype watch I have ever purchased. I have let it go since, and there is one main reason for that besides just getting bored of it long term, which happened also.

The digital subdial. Completely inadequate, useless, disappointing, frustrating and other matching phrases to continue.
The problem with the digital screen is legibility. You can barely see it with young, healthy eyes; forget about reading it properly once you're in the age where eyesight starts to lose its youthful strength.
The fact that the hands completely cover up the screen several times a day is just the last nail to the coffin, or to be a little bit more positive, the chef's kiss, the cherry on top, the last straw and other matching phrases to continue.

It took me a longer-than-usual time to sell the watch tho, because I quite liked it and I still think it looks amazing.
It's big, but it wears G-Shock big, which is always fine. It is comfortable on the resin strap, lightweight of course, and as I always had a thing for monochrome black watch dials, well, I have fallen in deep with my Casioak, and felt bad for selling it.
I bought the watch to be a gym watch, and in the gym I am in dire need of the stopwatch and countdown timer, as I must know to the exact second how much time I wasted scrolling on my phone while keeping one of the busy machines from being used by others, so the small, unreadable screen was a dealbreaker.

As for the Royal Oak resemblance, frankly, I didn't care much about that. I don't really see that in the design, maybe if I really squint my eyes I can see something that resembles an Offshore, but really, they are speaking a completely different design language, and I think that is for the best.