Kensington Watches
Casio G-SHOCK GG-B100X-1AER Master Of G Mudmaster Black Strap Watch - W17640

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Casio

Casio G-SHOCK GG-B100X-1AER Master Of G Mudmaster Black Strap Watch - W17640

Ref. GG-B100X-1AER

Among our 136 Casio watchesThis watch£349
Premium

Sits in Casio’s upper tier here — more premium than three quarters of the Casio watches we list, which start at £25.

Price range £25 to £919 across 136 Casio watches in stock.

The Mudmaster sits at the serious end of the Master of G line — the range Casio developed for people whose work or terrain makes an ordinary watch a liability. The GG-B100X is built around a Carbon Core Guard structure: a high-rigidity carbon case with a three-layer resin bezel carrying carbon fibre inserts, a design profile the retailer copy notes has been updated over older GG-B100 generations. The jug-handle bezel shape draws from the fuel jerry cans used on serious off-road vehicles, which sounds like marketing until you see it in person and the logic becomes obvious. At 51.3mm across and 55.4mm lug to lug, this is not a watch that hides. Yet at 93 grams it sits lighter than its dimensions suggest, because the bio-based carbon and resin construction carries far less mass than steel of equivalent bulk would. The sensor suite — compass, altimeter, barometer, thermometer, step counter — is paired with Bluetooth and the Casio app's Mission Log function, which stitches the watch's altitude data together with GPS route data from a paired phone, a genuinely useful feature rather than a specification for its own sake. The dual LED backlight illuminates analogue and digital displays together, so the watch is legible in full darkness without the awkward partial illumination that undermines some mixed-display designs.

Reference
GG-B100X-1AER
Brand
Casio
Collection
G-Shock
Case size
51.3mm
Case thickness
19.4mm
Case material
Carbon
Case shape
Round
Dial
Black
Functions
Stopwatch, Countdown timer, Alarm, Backlight, World time, Perpetual calendar, Bluetooth, Step counter, Compass, Thermometer, Altimeter, Dual display, Digital display
Water resistance
200m
Bracelet / strap
Rubber strap
Strap colour
Black
Retailer
Goldsmiths
Additional specifications
Lug-to-lug
55.4mm
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.

All Casio watches

Also in 6 collections

This watch appears in the Casio G-Shock range (84), Back in Stock (4,683), Watches 44mm and Over (827), Sports Watches (800), Dive Watches (568) and All Black Watches (315).

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
  • 55.4mm lug-to-lug keeps the 51.3mm case wearable
  • Luminous hands and markers for low light
  • Second time zone for travelling
  • One of Casio's more premium watches

Worth knowing

  • 51.3mm is a large watch with real presence
  • 19.4mm thick, so it will not disappear under a cuff
Best forDivingSwimmingTravel
Less suited toSmall wristsUnder a shirt cuff

Casio G-SHOCK GG-B100X-1AER Master Of alternatives

Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.

G-SHOCK GG-B100X-1AER Master Of G Mudmaster Black Strap Watch - W17640 compared with 2 alternatives from other brands
SpecificationThis watchG-SHOCK GG-B100X-1AER Master Of G Mudmaster Black Strap Watch - W17640GG-B100X-1AERGarminInstinct 3 010-03020-03 50mm AMOLED GPS Smartwatch - Limited Edition - W47380010-03020-03TissotT-Pocket Savonnette 48.5mm Mens Pocket WatchT8624101929200
Price£349£350£335
Case size51.3mm50mm48.5mm
Water resistance200m100m30m
MovementQuartzQuartzQuartz
StrapRubber strapSilicone strapStainless steel bracelet
This watch
  • Rated shallower
  • Rated shallower
  • Wears smaller

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 explained

Will 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 compared

Does 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 compared

Will 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 wrist

Is 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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