Introduction
The Citizen Eco-Drive One ref. AR5024-01E is a watch that defies physics. At just 2.98mm thick, it’s the world’s thinnest solar-powered watch—and one of the thinnest mechanical-looking watches ever made. But thinness alone doesn’t make a watch worth buying. In this review, we’ll break down the resale data, the hype cycle, and whether this trust-fund-friendly piece is a hold or a flip. Spoiler: it’s a hold for the minimalist collector, but don’t expect it to moonwalk on the secondary market.
Citizen has been pushing the boundaries of Eco-Drive technology since the 1990s, but the Eco-Drive One line, launched in 2017, was their answer to the ultra-thin dress watch segment dominated by Piaget and Jaeger-LeCoultre. The ref. AR5024-01E features a black dial with minimalist indices, a titanium case and bracelet, and a sapphire crystal. It’s a watch that disappears on the wrist—literally and figuratively. For the young collector who values engineering over flash, this is a sleeper hit. But does it have staying power? Let’s dig into the numbers.
Manufacture History
Citizen was founded in 1918 in Tokyo, Japan, and has grown into one of the world’s largest watch manufacturers. The company is best known for its Eco-Drive technology, which uses any light source to power the watch, eliminating the need for battery changes. The Eco-Drive One line represents the pinnacle of this technology, combining solar efficiency with a case thickness under 3mm. Citizen’s in-house engineering team spent years developing the ultra-thin solar cell and movement, resulting in a watch that is both a technical marvel and a wearable piece of art.
Movement
The Citizen Caliber E031 is a solar quartz movement developed entirely in-house. It uses a lithium-ion cell that charges from any light source, providing up to 8 months of power reserve on a full charge. The movement is incredibly slim, allowing the entire watch to be under 3mm thick. While there is no visible finishing—this is a quartz movement after all—the engineering is the star. The E031 is accurate to within ±15 seconds per month, though in practice with regular light exposure, it often performs better. It is not COSC-certified, but for a solar quartz, it’s more than adequate for daily timekeeping.
Specifications
- Case diameter: 37mm
- Case thickness: 2.98mm
- Lug-to-lug: 44mm
- Case material: Titanium
- Crystal: Sapphire
- Water resistance: 50m
- Lume: None
- Bracelet/Strap: Titanium bracelet with deployant clasp
Wrist Feel
The Citizen Eco-Drive One is almost unsettlingly light. At just 30g (including bracelet), it feels like wearing nothing at all—which is the point. The titanium case and bracelet are brushed to a matte finish, and the thin profile means it slides effortlessly under a dress cuff. The bracelet is comfortable but has a slight rattle due to the hollow end links, a compromise for weight savings. The deployant clasp is secure but can be fiddly to adjust. Overall, it’s a watch you forget you’re wearing, which is either a compliment or a criticism depending on your preference for wrist presence.
Accuracy
Quartz accuracy is typically within ±15 seconds per month, but the Eco-Drive system adds a variable: if the watch is kept in low light, the power reserve drops and accuracy can drift slightly. In normal daily wear with adequate light exposure, expect ±10 seconds per month. It’s not COSC-certified, but for a solar quartz, it’s more than adequate for daily timekeeping.
Occasions
The Eco-Drive One is best suited for dress and formal occasions, but its lightweight nature makes it a great daily wearer for those who prefer a minimalist aesthetic. It’s not a sports watch—50m water resistance means you can wash your hands, but don’t take it swimming. Pair it with a suit or a casual button-down, and it will disappear on your wrist.
Wrist Presence
2/5 – The watch is so thin and light that it barely registers on the wrist. It’s a stealth piece for those who want to know they’re wearing a marvel of engineering without broadcasting it. On a NATO or leather strap, it might gain a bit more presence, but the titanium bracelet keeps it under the radar.
Reference Variants
The Eco-Drive One line includes several dial colors: the AR5020-01E with a blue sunburst dial, the AR5023-01E with a silver dial and rose gold-tone accents, and the AR5025-01E with a white dial. All share the same ultra-thin case and titanium bracelet.
Family References
Other models in the Eco-Drive One family include the AR5020-01E, AR5023-01E, and AR5025-01E.
Other Notable Citizen Models
Citizen’s catalog is vast, but standout models include the Promaster Diver BN0150-28E (a rugged ISO-certified diver), the Chronomaster AQ4020-54A (a high-accuracy quartz with perpetual calendar), and the Attesa CC4025-82E (a GPS-synced titanium chronograph).
Similar Watches
If you’re considering the Eco-Drive One, you might also look at the Piaget Altiplano Ultimate Concept (the thinnest mechanical watch, but at a vastly higher price point), the Jaeger-LeCoultre Master Ultra Thin Moon (a classic dress watch with a mechanical movement), or the Bulova Precisionist 96B257 (a quartz watch with a sweeping seconds hand, but much thicker).
Homages
For a fraction of the price, the Skagen Holst SKW6193 offers a similar ultra-thin quartz experience, though with mineral crystal and lower build quality. It’s a good entry point for those who want the look without the investment.
Investment Value
The MSRP of the Citizen Eco-Drive One AR5024-01E is $1,200, and current retail prices are stable at that level. On the pre-owned market, you can find examples ranging from $700 to $1,000, depending on condition and box/papers. The trend is stable—this is not a watch that appreciates, but it also doesn’t depreciate rapidly. Auction history is minimal; when it does appear, it sells near the pre-owned retail range. Our hold recommendation: keep it if you appreciate the engineering and want a unique conversation piece. Flip only if you find a buyer who values thinness over brand prestige. The secondary market is soft, so don’t expect a quick profit.
Service Interval
Citizen recommends a service every 5 years, which typically involves a battery (or capacitor) replacement and gasket change. The approximate cost is $150, and while any competent watchmaker can handle it, authorized centers are recommended for water resistance testing.
Price Range
The price range for the AR5024-01E is $700 to $1,200. For the trust-fund-baby buyer, this is a low-risk entry into ultra-thin horology. It won’t appreciate, but it won’t depreciate much either. Buy pre-owned to save $300–$500.
Pros and Cons
Pros: World’s thinnest solar watch, extremely lightweight titanium construction, no battery changes ever, sapphire crystal at this price point, unique engineering story.
Cons: Hollow end links feel cheap, no lume, 50m water resistance is barely splash-proof, bracelet lacks micro-adjust, resale market is thin.
Final Verdict
The Citizen Eco-Drive One AR5024-01E is a triumph of engineering over ego. It’s not a watch that screams for attention—it whispers. For the collector who values innovation and minimalism, it’s a worthy addition. But if you’re looking for a hype piece that flips for profit, look elsewhere. This is a hold for life, or at least until the next generation of ultra-thin solar watches arrives.
