By BENJAMIN ROMAN

The devil’s in the details, the old saying goes. And Pearl Izumi claims the subtle details in the design of its Infini T ($55, www.pearlizumi.com) separate it from the crowd of breathable technical tops. I put it through a series of warm-weather runs and hikes over the last several weeks to see if it’s truly a standout.

You know that t-shirt you love so much because it fits just right? This top manages to channel some of that mojo. The fabric is silky smooth, and the fit is streamlined but not restrictive. And the Infini T wins extra design points for the angle-cut cuffs that keep your hands bunch-free, plus a soft baffle inside the neck zip that prevents chafing.

I was seriously impressed by how well this top breathes. Perfectly placed Direct-Vent panels suck moisture out at the neck, side, and arms, and the body fabric never produced that clammy feeling that plagues some “wicking” fabrics. So don’t be fooled by the long-sleeve design — this is a top to keep you cool while offering some sun and wind protection. (In contrast, it will not keep you warm on a chilly day.)

My only complaint was a slightly scratchy feeling of the mesh material when worn without a liner layer. But, fortunately, the panels aren’t in chafe-prone locations, so it’s a minor gripe.

The Ultra-Sensor Transfer fabric is a finely woven blend of polyester and bamboo carbon fiber, which is a departure from the standard synthetic materials found in most wicking clothing. This is an environmental plus (since bamboo is one of the most sustainable raw materials available), but Pearl Izumi claims it also has a more practical advantage over synthetic fabrics: natural antimicrobial properties to help prevent smelly gear.

This seemed too good to be true, so I gave a real-world test. After a long run, I wadded the shirt into a ball and left it in a corner for a couple days. And the result? Not exactly dryer fresh, but impressively funk-free.

The bottom line: Pearl Izumi’s Long Sleeve Infini T is a well-fitting and highly breathable technical top, with the added environmental and hygiene benefits of bamboo fabric.

—Contributor Benjamin Roman is a writer and design consultant from Venice, Calif.