CASIO EDIFICE EFS-S660D-1ADF SOLAR CHRONOGRAPH STAINLESS STEEL MEN WATCH
EFS-S660D-1ADF
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- 1 Year Warranty
The EDIFICE EFS-S660D-1ADF is a motorsport chronograph built around a case measuring just 38.3mm wide and 11.6mm thick. That is unusually compact for a chronograph, and it is the point of the watch: the tracking functions of a driver's watch in a case that does not dominate the wrist. A tachymeter runs around the bezel for calculating average speed, and the textured dial is finished to let enough light through to keep the solar cell charging.
The layout puts the chronograph seconds hand at the centre rather than on a sub-dial, so timing is read across the full width of the dial to 1/20 of a second. Running seconds move to a sub-dial instead, joined by sub-dials for stopwatch 1/20 seconds and stopwatch minutes. A blue centre seconds hand is the only colour on an otherwise all-steel watch.
Specification is above what the size suggests: sapphire crystal with anti-reflective coating, a solid stainless steel case and bracelet with a one-touch three-fold clasp, 100-metre water resistance, and solar charging that runs roughly five months from a full charge with no further light.
At a Glance
- BrandCasio EDIFICE
- LineSolar Powered Chronograph
- ModelEFS-S660D-1ADF
- Module5334
- Case Size45.3 × 38.3 × 11.6 mm
- Weight129g
- Case & BandStainless Steel
- GlassSapphire, Anti-Reflective
- BezelTachymeter
- Stopwatch1/20 Second
- PowerSolar Powered
- Water Resistance100m (10 BAR)
Why You'll Love It
- 38.3mm is the headline. Chronographs usually run 42mm and up because of the sub-dial layout, so a full three-register chronograph in a case this size is genuinely hard to find.
- Sapphire crystal with anti-reflective coating is a specification you normally step up several price tiers to get. It resists scratching far better than mineral glass and cuts glare when reading the dial at an angle.
- Solar charging means no battery changes and no service interval for power — roughly five months of running from a full charge even with no further light exposure.
- The centre chronograph seconds hand is a deliberate readability choice. Timing runs across the full dial rather than in a small sub-dial, which is far easier to read at a glance while doing something else.
- A tachymeter bezel turns elapsed time into average speed over a known distance — the original reason a driver's watch existed, and still the quickest way to do the calculation without a phone.
- At 11.6mm thick it slips under a cuff, so the watch works at a desk as easily as at a track day.
- The blue centre seconds hand is the only colour on the watch, which keeps an all-steel chronograph from reading as anonymous.
Perfect For
- Motorsport Enthusiasts
- Smaller Wrists
- Daily Office Wear
- Business to Weekend
- Sapphire Crystal Seekers
- Solar Watch Users
- First Chronograph
- Graduation Gift
Key Features
- 1/20-second chronograph — measuring capacity of 59 minutes 59.95 seconds, with elapsed time, split time and 1st-2nd place timing. The chronograph seconds hand sits at the centre of the dial for full-width readability.
- Tachymeter bezel — calculates average speed over a known distance directly from elapsed time.
- Sapphire crystal with anti-reflective coating — high scratch resistance with reduced glare when reading the dial off-axis.
- Solar powered — charges from any light source with no battery replacement. Approximately five months of operation from a full charge until the hands stop, with a low battery alert.
- Compact 38.3mm case at 11.6mm thick — 45.3mm lug to lug and 129 grams on the steel bracelet.
- Solid stainless steel case, bezel and bracelet — with a one-touch three-fold clasp, adjustable from 150mm to 205mm.
- Three-hand, three-dial layout — hour, minute and stopwatch seconds hands over sub-dials for timekeeping seconds, stopwatch 1/20 seconds and stopwatch minutes, plus a date display.
- 100-metre water resistance (10 BAR) — rated for swimming and snorkelling. Not intended for diving.
- Textured dial finish — treated for depth while still transmitting enough light to keep the solar cell charging.
Technical Specifications
The Casio EDIFICE EFS-S660D-1ADF is a solar-powered analog chronograph on module 5334. The stainless steel case measures 45.3 × 38.3 × 11.6mm and weighs 129 grams, with sapphire crystal carrying an anti-reflective coating, a tachymeter bezel and a stainless steel bracelet with one-touch three-fold clasp adjustable from 150mm to 205mm, rated to 100 metres of water resistance. The display runs three hands over three sub-dials with a date window, and the chronograph measures to 1/20 of a second with a capacity of 59 minutes 59.95 seconds. Power is solar with no battery replacement, giving approximately five months of operation from a full charge until the hands stop, and accuracy is ±20 seconds per month.
| Model Number | EFS-S660D-1ADF |
| Case & Bezel Material | Stainless Steel |
| Case Size (L × W × H) | 45.3 × 38.3 × 11.6 mm |
| Weight | 129g |
| Glass | Sapphire Crystal with Anti-Reflective Coating |
| Bezel Features | Tachymeter |
| Water Resistance | 100 Metres (10 BAR) |
| Display Type | Analog |
| Hands | 3 Hands (Hour, Minute, Stopwatch Seconds) |
| Sub-Dials | 3 (Timekeeping Seconds, Stopwatch 1/20 Second, Stopwatch Minutes) |
| Date | Date Display |
| Centre Seconds Hand | Blue |
| Stopwatch | 1/20 Second |
| Measuring Capacity | 59'59.95" |
| Measuring Modes | Elapsed Time, Split Time, 1st-2nd Place Times |
| Power Supply | Solar Powered |
| Run Time | Approx. 5 Months from Full Charge |
| Battery Alert | Low Battery Alert |
| Accuracy | ±20 Seconds Per Month |
| Material | Stainless Steel |
| Clasp | One-Touch 3-Fold Clasp |
| Compatible Band Size | 150mm to 205mm |
Best Matched With
- Navy Suit
- White Oxford Shirt
- Grey Blazer
- Racing Jacket
- Dark Denim
- Suede Driving Shoes
- Black Knit Polo
Frequently Asked Questions
How do I use the tachymeter?
Start the chronograph as you pass a known start point and stop it after covering a known distance — a kilometre or a mile. Read the number the chronograph seconds hand points to on the tachymeter scale, and that is your average speed over that distance in units per hour. It works for any repeatable measure, not just driving.
Why is the chronograph seconds hand in the centre?
Most chronographs put running seconds in the centre and timing on a sub-dial. This one reverses that: the chronograph seconds hand sweeps the full dial while running seconds sit in a sub-dial. Timing is far easier to read across the whole face than in a 10mm register, which matters when you are glancing at it mid-activity.
Does this watch ever need a battery change?
No. Solar charging draws from any light source, indoor or outdoor, so there is no scheduled battery replacement. From a full charge it runs approximately five months before the hands stop, even with no further light exposure, and a low battery alert warns you before that point.
How much better is sapphire than mineral glass?
Substantially harder — sapphire resists scratching from keys, stone and grit that would mark mineral glass over time, which is why it is normally found further up the range. The trade-off is that a deep scratch cannot be polished out the way it sometimes can on mineral. The anti-reflective coating here also cuts glare when you read the dial at an angle.
Is 38.3mm too small for a chronograph?
It is deliberately compact, and it is the reason to choose this model. Three-register chronographs usually need 42mm or more to lay out the sub-dials, so 38.3mm across and 45.3mm lug to lug suits wrists from roughly 15cm to 18cm properly rather than overhanging them. At 11.6mm thick it also clears a shirt cuff, which larger chronographs rarely do.
Can I swim with it?
Yes. 100-metre (10 BAR) water resistance covers swimming and snorkelling. It is not intended for diving. Do not operate the crown or the chronograph pushers while the watch is wet.
What is the difference between the EFS-S660D-1ADF and the EFS-S660PB-1ADF?
Same module, same case size, same sapphire crystal and the same 100-metre rating. The D-1ADF is the stainless steel version — steel case, steel bracelet, blue centre seconds hand. The PB-1ADF runs a grey ion-plated case with a resin band and a red centre seconds hand, which reads sportier and sits lighter on the wrist.
Is the bracelet adjustable?
Yes. The stainless steel bracelet fits wrists from 150mm to 205mm and is resized by adding or removing links. City Chain offers complimentary bracelet sizing at any outlet — bring your warranty book along for the service.
How accurate is it?
±20 seconds per month, which works out to a few minutes of drift across a year. Correcting it takes a moment with the crown.
Why Buy from City Chain Singapore
- Authorised Retailer Official Casio warranty
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