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Casio AQ-S820W-3BVEF Tough Solar Green Strap Watch - W17564
Ref. AQ-S820W-3BVEF
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Stepping up in the same colour and case shape
The AQ-S820W sits within Casio's ana-digi sport lineage — a format the brand has refined for decades — pairing analogue hands with a dedicated digital panel at six o'clock to keep the full function set readable without crowding the dial. The calibre 5745 charges from any light source and holds that charge for up to ten months in darkness, which means battery anxiety simply does not arise. At 50.1mm across and 46 grams, it wears far lighter than those dimensions suggest; the resin case loses the sense of mass that a metal watch of similar size would carry. The matte green case and strap read as a coordinated unit against the black dial, and the Neobrite on the hands — supplemented by an orange LED backlight — means the watch remains usable well after dark.
- Reference
- AQ-S820W-3BVEF
- Brand
- Casio
- Collection
- Timeless
- Case size
- 50.1mm
- Case thickness
- 12.7mm
- Case material
- Resin
- Case shape
- Round
- Dial
- Black
- Crystal
- Acrylic
- Movement
- Solar
- Functions
- Chronograph, Day-date, Stopwatch, Countdown timer, Alarm, Backlight, World time, Solar powered, Dual display
- Water resistance
- 100m
- Bracelet / strap
- Rubber strap
- Strap colour
- Green
- Clasp
- Buckle
- Lume
- Luminous
- Retailer
- F.Hinds
Additional specifications
- Lug-to-lug
- 52.5mm
- Weight
- 46g
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 5 collections
This watch appears in Back in Stock (3,734), Chronograph Watches (953), Watches 44mm and Over (603), Watches Under £100 (439) and Solar & Kinetic Watches (173).
Manufacturer’s guarantee
What the specifications mean
Strengths
- 100m water resistance covers swimming and watersports
- 52.5mm lug-to-lug keeps the 50.1mm 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
- 50.1mm is a large watch with real presence
- Acrylic crystal marks easily, though it polishes out
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
Yes. At 100m it is rated for swimming and snorkelling, though not for diving.
Water resistance explainedWill the glass scratch?
Yes, but it polishes out. Acrylic marks easily and a scratch can be buffed away at home, which is why vintage-style watches still use it.
Sapphire, mineral and acrylic comparedDoes it need a battery?
No. It charges from light, and the cell behind that is designed to last a decade or more.
Quartz, automatic and solar comparedWill it fit my wrist?
Lug-to-lug is 52.5mm, which suits wrists from roughly 17.5cm (7 inches) upward.
Lug-to-lug decides fit more than case diameter does.
How to size a watch to your wristCheapest place to buy
F.Hinds is the only UK retailer we track stocking this reference, so there is nothing to compare it against today.
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