The Citizen Eco-Drive One | family history
The Eco-Drive One proved that Eco-Drive is not only a mass-market technology. At 2.98mm case height, it was the world's thinnest solar watch at launch in 2015. The H001 caliber was designed as a bespoke ultra-thin module; the grade-5 titanium case maintains structural integrity at that height. A technical proof-of-concept that happens to be wearable.
Citizen’s ultra-thin solar statement: 2.98mm case height at launch (the world’s thinnest solar watch). H001 calibre, grade 5 titanium. A proof that Eco-Drive is not only a mass-market technology: the engineering target here is luxury-tier slimness.
2015 · Eco-Drive One launch
Citizen presented the Eco-Drive One at Baselworld 2015. The 2.98mm case height made it thinner than many dress watch movements alone. The H001 caliber's photovoltaic cell is visible through the dial; the movement architecture was designed ground-up for the constraint rather than adapted from an existing module. A world record claim that held for several years.
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Two honest questions for any Eco-Drive One buyer:
- Is 2.98mm too thin to be durable? Citizen engineered the grade-5 titanium case specifically for this constraint. It is not fragile in normal wearing conditions. It is not a watch for manual labor or contact sports. At this price and this thinness, treat it accordingly.
- Eco-Drive One vs. Piaget Altiplano for ultra-thin? The Piaget Altiplano is a mechanical ultra-thin in gold at multiples of the Eco-Drive One's price, with strong collector and secondary-market standing. The Eco-Drive One is solar-powered titanium at a fraction of the price. Different briefs. The Eco-Drive One is the choice for someone who wants ultra-thin practicality; the Altiplano is for someone who wants ultra-thin prestige.
Related families: Citizen Promaster Marine · Longines Presence
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The Eco-Drive One AQ4060 is a world record ultra-thin solar watch at 2.98mm total case thickness. The movement is 1.0mm thick. A genuine engineering achievement from Citizen: the thinnest solar watch ever made.
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Eco-Drive One AQ4060 -- 2.98mm total thickness, world's thinnest solar watch, a genuine engineering record.
- The case for it:
- The 1.0mm movement inside a 2.98mm case is a documented world record. Citizen achieved this by developing new techniques for movement miniaturization. As an engineering object the Eco-Drive One is comparable in concept to the Bulgari Octo Finissimo -- a record-setting ultra-thin from an unexpected maker.
- Consider instead if:
- Quartz solar at a premium price competes against dress watches with mechanical movements. Buyers who want ultra-thin should compare the Citizen against the Piaget Altiplano entry tier -- the horological heritage is different but the market is the same.
Rankings last reviewed 2026-06-07. Editorial perspective only. Not financial advice.