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Casio G-Shock GA-100CY-1AER Caution Yellow Strap Watch - W17406
Ref. GA-100CY-1AER
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Stepping up in the same colour and case shape
The GA-100 arrived in 2010 as G-Shock's answer to a gap in its own lineup: something that read analogue at a glance but carried the full digital function set underneath. The "Caution Yellow" version takes that tool-watch premise literally, lifting its colour language from industrial warning signage — high-visibility yellow against matte black, the palette of construction sites and safety vests. It is a deliberate visual argument rather than a styling exercise. At 51.2mm wide and 55.0mm lug-to-lug it occupies real wrist space, but at 72 grams the hollow resin structure makes those dimensions feel misleading in practice — it sits lighter than watches half its footprint. Low-light reading depends not on painted lume but on an integrated amber LED backlight that fires automatically when the wrist tilts toward the face, which is a more consistent solution for a watch used in genuinely dark conditions.
- Reference
- GA-100CY-1AER
- Brand
- Casio
- Collection
- G-Shock
- Case size
- 51.2mm
- Case thickness
- 16.9mm
- Case material
- Resin
- Case shape
- Round
- Dial
- Black
- Crystal
- Mineral
- Movement
- Automatic
- Functions
- Chronograph, Day-date, Stopwatch, Countdown timer, Alarm, Backlight, World time, Perpetual calendar, Dual display
- Water resistance
- 200m
- Bracelet / strap
- Rubber strap
- Strap colour
- Black
- Clasp
- Buckle
- Lume
- Luminous
- Retailer
- F.Hinds
Additional specifications
- Lug-to-lug
- 55mm
- Warranty
- 2 years
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.
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
- 55mm lug-to-lug keeps the 51.2mm case wearable
- Luminous hands and markers for low light
- Second time zone for travelling
- Sits in the lower half of Casio's range as we list it
Worth knowing
- 51.2mm is a large watch with real presence
- 16.9mm thick, so it will not disappear under a cuff
Compare alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | GA-100CY-1AER |  PEWJK21951011 |  ME3081 |
|---|---|---|---|
| Price | £100 | £110 | £139 |
| Case size | 51.2mm | 48mm | 50mm |
| Water resistance | 200m | 30m | 50m |
| Movement | Automatic | Automatic | Automatic |
| Strap | Rubber strap | Leather 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.
Will the glass scratch?
It can, over time. Mineral glass handles daily wear but will pick up fine scratches that sapphire would not.
Does it need a battery?
No. It is automatic — the motion of your wrist winds it, and there is no cell to replace.
Will it fit my wrist?
Lug-to-lug is 55mm, which suits wrists from roughly 18.5cm (7¼ inches) upward.
Lug-to-lug decides fit more than case diameter does.
Is it a men's or women's watch?
Listed as men's.
Cheapest place to buy
F.Hinds is the only UK retailer we track stocking this reference, so there is nothing to compare it against today.
Who are F.Hinds?
F.Hinds has been run by the same family since 1856 and is now in its fifth generation, with more than 115 shops across England and Wales. They are a member of the Responsible Jewellery Council and an Authorised Diamond Dealer.
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