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Casio F-B100W-3AEF Green Activity Tracker - W17635
Ref. F-B100W-3AEF
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Stepping up in the same dial colour
The F-91W has been one of the most recognisable digital watches on the planet since the late 1980s, and this is its direct successor — Casio's answer to the one consistent complaint about the original: that it sat too small on a modern wrist. The F-B100W keeps the angular rectangular case, the symmetrical four-button layout and the monochrome display of its predecessor, but grows the footprint to 38.1mm and adds two things the F-91W never had: a Bluetooth link that syncs time automatically through a paired phone several times daily, and a step counter that reports progress on the main display. At 26 grams and 8.8mm thick it disappears on the wrist in a way most activity trackers cannot manage. The green strap is cut with inner slits to improve airflow during wear — a practical modification that makes a real difference over a long day. Where old Casio digitals used a dim side-mounted bulb, this one has a full amber LED backlight that lights the entire display cleanly in the dark.
- Reference
- F-B100W-3AEF
- Brand
- Casio
- Collection
- Casio
- Case size
- 38.1mm
- Case thickness
- 8.8mm
- Case material
- Resin
- Case shape
- Rectangular
- Dial
- Black
- Crystal
- Mineral
- Movement
- Automatic
- Functions
- Stopwatch, Countdown timer, Alarm, Backlight, World time, Bluetooth, Step counter, Digital display
- Bracelet / strap
- Rubber strap
- Strap colour
- Green
- Clasp
- Buckle
- Lume
- Luminous
- Retailer
- F.Hinds
Additional specifications
- Lug-to-lug
- 41.9mm
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 Automatic Watches (1,648), Watches Under £100 (564), Rectangular & Square Watches (426) and Automatic Watches Under £500 (302).
Manufacturer’s guarantee
What the specifications mean
A mechanical watch for everyday wear.
Strengths
- 38.1mm suits most wrists
- 8.8mm is unusually slim for a 38.1mm case
- 41.9mm lug-to-lug keeps the 38.1mm case wearable
- Luminous hands and markers for low light
- Second time zone for travelling
Casio F-B100W-3AEF Green Activity Tracker alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | F-B100W-3AEF | 47516/GD/TUR | RA29-2182 |
|---|---|---|---|
| Price | £55 | £65 | £65 |
| Case size | 38.1mm | 38mm | 40mm |
| Water resistance | — | 50m | — |
| Movement | Automatic | Automatic | Automatic |
| Strap | Rubber strap | — | Silicone strap |
| This watch |
|
|
Your new watch
Frequently asked questions, and things you should know about this watch
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 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 41.9mm, which suits wrists from roughly 15cm (6 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 unisex, and at this size it suits any wrist that takes the dimensions.
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.
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