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Casio Master Of G-Land GDG-B100 Series 63.6mm x 49.6mm Mens Watch Black Dial
Ref. GDG-B100-1A3ER
Sits in Casio’s upper tier here — more premium than three quarters of the Casio watches we list, which start at £20.
Price range £20 to £919 across 152 Casio watches in stock.The Mudman line within Master of G has always occupied the extreme end of the range — built not for surf or altitude but for dirt, specifically for conditions where grit and silt work their way into everything. The GDG-B100 carries that brief further by drawing its bumper guard architecture from off-road vehicle protection, with an oversized multi-component structure designed to absorb impact and exclude mud, and buttons large enough to operate confidently in gloves. At 49.6mm wide it is a large watch, but the Carbon Core Guard and bio-based resin construction hold the whole thing to 66 grams, so it sits against the wrist rather than hanging from it. The MIP LCD is the right screen for this application — readable in full sunlight where a standard backlit display disappears — and the red auto-LED backlight preserves night vision rather than destroying it, which matters if you are actually working in darkness. Bluetooth sync brings the timekeeping to within a second when connected, with the module drifting no more than ±15 seconds per month when running independently.
- Reference
- GDG-B100-1A3ER
- Brand
- Casio
- Collection
- Master of G Mudman
- Case size
- 49.6mm
- Case thickness
- 16.2mm
- Case material
- Resin
- Case shape
- Octagonal
- Dial
- Black
- Crystal
- Mineral
- Movement
- Quartz
- Calibre
- 3587
- Functions
- Stopwatch, Countdown timer, Alarm, Backlight, World time, Perpetual calendar, Bluetooth, Step counter, Digital display
- Water resistance
- 200m
- Bracelet / strap
- Rubber strap
- Strap colour
- Blue
- Clasp
- Buckle
- Lume
- Luminous
- Retailer
- Goldsmiths
Additional specifications
- Lug-to-lug
- 63.6mm
- Weight
- 66g
Learn more about Casio
Tadao Kashio founded Kashio Seisakujo in Tokyo in 1946 as a machine shop. The company's first success was a finger ring that held a cigarette, and its second was the 14-A of 1957 — the world's first all-electric compact calculator, which used solenoids rather than gears.
Casio entered watchmaking in 1974 with the Casiotron, a digital watch with an automatic calendar that knew the varying lengths of months. The company approached watches as an electronics manufacturer rather than a horological one, and that difference produced the G-Shock.
The G-Shock came from a single engineer, Kikuo Ibe, who broke a watch his father had given him and set out to build one that could not break. The specification was three tens: survive a ten-metre drop, ten bars of water pressure, and ten years of battery life. It took over two hundred prototypes, and the solution was suspending the module inside the case on a cushioned internal structure rather than mounting it rigidly. The DW-5000C shipped in 1983.
It became one of the most durable product designs in any category, adopted by militaries, emergency services, and skateboarders alike, and Casio has since added solar charging, radio and GPS timekeeping, Bluetooth, and full-metal and carbon variants.
Casio also produces the Edifice, Pro Trek, and Oceanus lines, and remains an independent Japanese public company.
- 1946
- Tadao Kashio founds the company in Tokyo.
- 1974
- The Casiotron is Casio's first digital watch.
- 1983
- The G-Shock DW-5000C survives Kikuo Ibe's three-tens brief.
- 1994
- The Frogman extends G-Shock to ISO dive certification.
Also in 4 collections
This watch appears in Watches 44mm and Over (802), Sports Watches (800), Dive Watches (572) and Dive Watches Under £300 (94).
Manufacturer’s guarantee
What the specifications mean
A watch built to be worn hard and got wet.
Strengths
- 200m water resistance, rated for actual diving
- Luminous hands and markers for low light
- Second time zone for travelling
- One of Casio's more premium watches
Worth knowing
- 49.6mm is a large watch with real presence
- 16.2mm thick, so it will not disappear under a cuff
Casio Master Of G-Land GDG-B100 alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | GDG-B100-1A3ER | DZ4582 | MK8184 |
|---|---|---|---|
| Price | £200 | £189 | £154 |
| Case size | 49.6mm | 51mm | 48mm |
| Water resistance | 200m | 100m | 100m |
| Movement | Quartz | Quartz | Quartz |
| Strap | Rubber strap | Stainless steel bracelet | Silicone strap |
| This watch |
|
|
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
Yes. At 200m it is rated for swimming, snorkelling and recreational diving.
Water resistance explainedWill the glass scratch?
It can, over time. Mineral glass handles daily wear but will pick up fine scratches that sapphire would not.
Sapphire, mineral and acrylic comparedDoes it need a battery?
Yes. It is quartz, so expect a battery change every two to three years at a jeweller.
Quartz, automatic and solar comparedWill it fit my wrist?
Lug-to-lug is 63.6mm, which suits wrists from roughly 18.5cm (7¼ inches) upward.
Lug-to-lug decides fit more than case diameter does.
How to size a watch to your wristIs it a men's or women's watch?
Listed as men's.
Cheapest place to buy
Goldsmiths is the only UK retailer we track stocking this reference, so there is nothing to compare it against today.
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