Terramar The Beast Half-Zip Baselayer

Most versatile

Brand: Terramar

Model: The Beast




Our take 

The thermoregulating Beast sometimes seemed smarter than us­. When we were cold, its polyester fibers contracted, mechanically tightening the weave to retain extra heat; when we were steaming, they loosened to let air in and sweat vapor out. The secret? ClimaSense Carbon, a nanoparticle treatment on the fabric that responds to your temperature and sweat levels. The company won’t say how it works, but we felt the effects on daylong Alaska ski tours with 40°F temp swings. The Beast’s sweet spot is active use around 15°F, but its temperature control and good-for-its-weight dry times also kept us in the comfort zone while skinning uphill in warmer weather.

The details 

Mesh inlays in the pits and a zipper that dips to the sternum vent heat. Drawbacks: Testers with long torsos found the cut too short, exposing their lower backs when they bent over, and the Beast doesn’t come in a women’s version.

Trail cred 

“Over days skinning across a glacier with a pack, I felt sweaty when the temps rose to the 20s or higher,” reports an Alaska tester. “But the top dried in 30 minutes as I set up camp.”