Editorial
At 2.98mm total thickness, the Eco-Drive One is one of the thinnest watches ever produced by any manufacturer. Citizen built it around a solar movement just 1mm thick, then wrapped everything in Grade 5 titanium to keep it light enough that you actually forget it is on your wrist. This is not a dress watch that happens to be thin , it is a feat of manufacturing discipline that most Swiss houses with far larger budgets have not matched.
Citizen introduced the Eco-Drive One in 2015 as a showcase of what its solar technology could achieve when thinness became the primary constraint. The H001 caliber required years of development to compress a functioning solar movement into a 1mm profile without sacrificing power reserve or reliability. Citizen had produced ultra-thin quartz pieces before, but the Eco-Drive One was a deliberate statement aimed directly at the ultra-thin mechanical watches from Piaget and Bulgari that were dominating press coverage at the time.
The AQ4060 variant uses a blue-tinted sapphire crystal and a refined dial that lets the architecture of the case speak rather than adding decorative noise. It remains in production, which is a reasonable signal that Citizen considers this a pillar reference rather than a limited exercise.
The case is 38.5mm but wears far smaller than that number suggests because the profile is so thin , buyers expecting a wrist-filling presence will be surprised. The titanium case is scratch-resistant compared to steel but the brushed finish shows contact marks over time and re-polishing requires a brand service center familiar with the geometry. Citizen rates the AQ4060 at 3ATM water resistance, which means rain and hand-washing are fine but swimming is not , the ultra-thin construction leaves no margin for deeper water pressure.
The solar charging requires periodic exposure to light; if stored in a dark watch box for weeks, the reserve will deplete, and the watch needs several hours of light exposure before it runs correctly again. Finally, the integrated bracelet on some configurations is matched very precisely to the case thickness, so aftermarket straps require careful selection to avoid looking awkward against the tapered lugs.
