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Casio Edifice EFK-100D-3AER Automatic Bracelet Watch - W17546
Ref. EFK-100D-3AER
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The Edifice line has long been Casio's home for quartz chronographs with motorsport posturing, so the EFK-100D-3AER represents a genuine pivot: a mechanical movement where a solar cell would normally sit. The NH35A inside is a Seiko-designed calibre trusted by the broader industry precisely because it is robust, straightforward to service, and accurate enough to satisfy most owners without fuss — an honest foundation for a watch positioned as Casio's entry into mechanical sports territory. At 39mm with a lug-to-lug of 43.5mm, it will sit neatly on smaller wrists that a 41mm or 42mm sports watch would overwhelm, and the integrated bracelet profile keeps it reading as a coherent piece rather than a case dropped onto a generic strap. The green dial carries a deeply textured electroformed finish that shifts character under different light — flat overhead it reads as a dark, almost muted tone; catch it at an angle and the surface becomes noticeably more present. The 12.5mm case height is the one compromise, perceptible on the wrist but the price of fitting a mechanical movement into this footprint. The exhibition caseback is worth a mention for a watch at this level: the rotor assembly is visible and the finishing is tidy enough that it rewards a look. Bracelet adjustment runs through standard split pins, and the push-button deployment clasp handles daily on and off without reaching for a tool.
- Reference
- EFK-100D-3AER
- Brand
- Casio
- Collection
- Edifice
- Case size
- 39mm
- Case thickness
- 12.5mm
- Lug width
- 20mm
- Case material
- Stainless steel
- Case shape
- Round
- Dial
- Green
- Crystal
- Sapphire
- Movement
- Automatic
- Calibre
- NH35A
- Functions
- Chronograph, Date
- Water resistance
- 100m
- Bracelet / strap
- Stainless steel bracelet
- Strap colour
- Silver
- Clasp
- Three-fold clasp
- Lume
- Luminous
- Retailer
- F.Hinds
Additional specifications
- Lug-to-lug
- 43.5mm
- Power reserve
- 41 hours
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 for everyday wear.
Strengths
- 100m water resistance covers swimming and watersports
- 39mm suits most wrists
- 43.5mm lug-to-lug keeps the 39mm case wearable
- Sapphire crystal, which resists scratching
- Luminous hands and markers for low light
Compare alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | EFK-100D-3AER |  SRPG27K1 |  70021 |
|---|---|---|---|
| Price | £179 | £220 | £199 |
| Case size | 39mm | 39.4mm | 41mm |
| Water resistance | 100m | 100m | 100m |
| Movement | Automatic | Automatic | Automatic |
| Strap | Stainless steel bracelet | Stainless steel bracelet | Stainless steel bracelet |
| Power reserve | 41 hours | 41 hours | 41 hours |
| This watch |
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|
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.
Will the glass scratch?
Unlikely. Sapphire is second only to diamond in hardness and shrugs off everyday marking.
Does it need a battery?
No. It is automatic — the motion of your wrist winds it, and there is no cell to replace.
How long does it run for when it's not worn?
About 41 hours fully wound — enough to survive a night off the wrist, but not a full weekend.
What size strap does it take?
20mm. Any strap of that width will fit, and on most modern watches quick-release bars make the swap a two-minute job with no tools.
Will it fit my wrist?
Lug-to-lug is 43.5mm, which suits wrists from roughly 15cm (6 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, though at 39mm it sits in the range that suits anyone.
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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