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Casio G- SHOCK Master of G-Land Mudmaster 55.4mm X 51.3mm Watch Brown
Ref. GG-B100XMH-5AER
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 "Master in Horizon Gold" is a limited edition within the Mudmaster line, its brown and gold palette drawn from the image of a sand horizon at low sun — an aesthetic choice that doubles as camouflage for the conditions this watch is built to take on. The Carbon Core Guard construction encloses the module in a carbon-reinforced shell, with the caseback adding a stainless steel layer beneath a glass-fibre resin outer cover specifically to block mud and grit from reaching the internals. At 104 grams, it carries less than the size suggests. The quad sensor suite — altimeter, barometer, compass, thermometer, and a 3-axis accelerometer — is paired with Bluetooth that does more than sync the time: when linked to the Casio app, the Mission Log overlays the watch's altitude readings against the phone's GPS track, producing a usable record of a route rather than just a timestamp.
- Reference
- GG-B100XMH-5AER
- Brand
- Casio
- Collection
- G-Shock Mudmaster
- Case size
- 55.4mm
- Case thickness
- 19.4mm
- Case material
- Stainless steel
- Case shape
- Round
- Dial
- Black
- Crystal
- Mineral
- Movement
- Automatic
- Calibre
- 5744
- Functions
- Chronograph, GMT
- Water resistance
- 200m
- Bracelet / strap
- Rubber strap
- Strap colour
- Brown
- Clasp
- Buckle
- Lume
- Luminous
- Retailer
- Goldsmiths
Additional specifications
- Lug-to-lug
- 55.4mm
- Weight
- 104g
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 6 collections
This watch appears in Back in Stock (4,868), Stainless Steel Watches (3,133), Automatic Watches (1,750), Chronograph Watches (1,199), Watches 44mm and Over (802) and Sports Watches (800).
Manufacturer’s guarantee
What the specifications mean
A mechanical watch built to be worn hard and got wet.
Strengths
- 200m water resistance, rated for actual diving
- 55.4mm lug-to-lug keeps the 55.4mm case wearable
- Luminous hands and markers for low light
- Second time zone for travelling
- One of Casio's more premium watches
Worth knowing
- 55.4mm is a large watch with real presence
- 19.4mm thick, so it will not disappear under a cuff
Casio G- SHOCK Master of alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | GG-B100XMH-5AER | 17430B59 |
|---|---|---|
| Price | £365 | £248 |
| Case size | 55.4mm | 55mm |
| Water resistance | 200m | 50m |
| Movement | Automatic | Automatic |
| Strap | Rubber strap | Stainless steel bracelet |
| 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?
No. It is automatic — the motion of your wrist winds it, and there is no cell to replace.
Quartz, automatic and solar comparedWill it fit my wrist?
Lug-to-lug is 55.4mm, 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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