Sapphire Solar Chrono Watch EFS-S640D-1AVUEF

The Watch

Casio is a powerhouse brand that began its journey in the watchmaking industry in 1974 with the launch of the first digital display watch, the Casiotron. Since then, the company has never stopped innovating, building an extensive lineup of timepieces for every kind of watch enthusiast. From the Casio Edifice collection comes this exceptional Solar Chrono Watch EFS-S640D-1AVUEF, designed for men's wrists. It features a round case crafted in black carbon fiber-reinforced resin with a diameter of 44.50 mm, a lug-to-lug length of 50.10 mm, a thickness of 13.30 mm, and a weight of 118 g. Inspired by the world of motorsport, this model embodies the speed and sophistication that define the Edifice line. It is fitted with a fixed stainless steel bezel graduated with a minute scale. The case is topped by a sapphire crystal with anti-reflective coating, protecting the dial from impacts while boosting indicator readability. The crown and two pushers at 2, 3, and 4 o'clock let you adjust all functions with ease. This timepiece features a screw-back case delivering water resistance of 10 ATM.

The Dial

This carbon dial wears a rich black with a captivating woven pattern. At its center, a seconds hand tracks chronograph seconds, flanked by two hands for hours and minutes. These hands, along with the indices beneath them, are treated with Neobrite for clear legibility in low-light environments. A minute track runs along the dial's edge, while a date window at 4 o'clock rounds out the display. The battery level indicator is integrated into the sub-seconds counter, joined by 24-hour and 30-minute counters at 12 and 9 o'clock. The brand signature is displayed at 3 o'clock.

Functions

Solar Power

Invisible solar cells built into the watch convert light into energy to power all functions. A rechargeable battery provides the capacity needed to keep running in low-light conditions.

Neobrite Coating

The hands and/or indices are coated with a fluorescent material that continues to glow in the dark after the watch has been exposed to a light source.

Stopwatch Function - 1/1 sec - 30 min

Timings are measured to the nearest second, up to a maximum duration of 30 minutes.

Battery Level Indicator

Displays the current battery level.

The Movement

This watch is powered by a Japanese-made solar movement. It delivers an accuracy of ±20 seconds per month and offers a power reserve of approximately 5 months from full charge to stopped hands.

The Bracelet

This stunning bracelet is crafted in brushed stainless steel with a sleek silver tone. The result of precision-assembled resistant links, its brushed finish enhances its inherent beauty. Easy to put on and take off, it fastens with a triple-folding clasp and fits wrists ranging from 150 to 205 mm.

Water Resistance

This model offers water resistance of 10 atmospheres, or 100 meters - making it a genuinely water-resistant timepiece. It's ready to splash around with you in any aquatic setting, from puddles to the pool. Showering, bathing, and recreational swimming? No problem. That said, our watchmaking experts note that while this model is water-resistant, it is not suitable for diving (professional or recreational) and should be kept away from high-pressure cleaning equipment. We also recommend avoiding use of the crown or pushers while submerged.