Citizen’s Latest Eco-Drive One Sports Watch Is Just 3.88 Millimeters Thick

Sean Tirman

Updated Tue, August 18, 2026 at 5:12 PM UTC

This award-winning watch, first introduced in 2016, gets an ultra-thin follow-up for 2026 that retains its exceptional movement.

Side view of a slim black metal watch case with a matching black metal link bracelet against a tan background.

If you buy from a link, we may earn a commission. Learn more

Way back in 2016 , when it was first introduced, we placed Citizen's Eco-Drive One among the best watches of the whole year.

Now, for 2026, Citizen has revived and refreshed that watch in a limited-edition run of the Citizen Eco-Drive One AR5065-54W . And while not quite as thin as the original, it remains one of the thinnest solar watches ever made.

Black Citizen wristwatch with green and black dial, rose gold hands and markers, and black metal link band. — The minimalist styling plays well with the incredibly thin silhouette. - Credit: Citizen

Slim tickings

The watch is crafted from a black-finished, brushed stainless steel, including its integrated bracelet. All told, the case measures just 3.88 millimeters thick.

For reference, most watches sit between 10 and 14mm, so this is a remarkable achievement by Citizen. And you might think that slenderness comes with some serious drawbacks. For the most part, you'd be incorrect.

Close-up of a Citizen watch face with black and green dial, rose gold hands and markers, and black case with rose gold screws. — The dial markings are kept as pared-down as possible, helping to keep the watch svelte while still easy to read. - Credit: Citizen

Although minimalist in its design, the watch functions and wears just like any other time-only watch. It has both hour and minute hands, and it features simple, albeit discernible, markings. It's also finished in a dressy overall style.

It even retains a classic crown for adjustments, albeit on the smaller side. And while I wouldn't recommend diving with it, its 50-meter water resistance rating means you shouldn't worry about it getting splashed in the rain.

Black metal watch band with a clasp and a crown on a tan background. — Yes, the case is really only 3.88mm thick. - Credit: Citizen

What's inside counts

The thinness of this watch comes down to one crucial factor: the slenderness of its internal movement. Housed inside its incredibly thin case is an even thinner 8826 Eco-Drive movement, which measures just 1.0 millimeters thick.

Those in the know will recognize what the "Eco-Drive" in its name means: this is a solar-powered watch. Built on a quartz system, this watch is powered by the sun (or any light source). That means it's even more convenient than typical quartz watches, as it never requires a battery replacement. When the battery is low, it just needs a little light to get going again.

Housed inside its incredibly thin case is an even thinner 8826 Eco-Drive movement, which measures just 1.0 millimeters thick.

As mentioned earlier, that ultra-slim movement is protected by a brushed stainless steel case (with a black finish that adds a bit more durability), but it also has an impact- and shatter-resistant sapphire crystal over the dial. That, of course, also gets an anti-reflective coating. And the integrated bracelet has a simple, classic foldover clasp.

There's just one big catch: the watch is limited to just 250 units worldwide. Total. If you have any hopes of snagging what Citizen calls a "marvel of micro engineering, powered entirely by light," you'll want to act quickly.