Get full access to Outside Learn, our online education hub featuring in-depth fitness, nutrition, and adventure courses and more than 2,000 instructional videos when you sign up for Outside+ Sign up for Outside+ today.
Our take Don’t let the dog days of summer keep from you hitting the trail. The F.K.T. II has an innovative system, known as Omni-Freeze Zero, to help you stay cool. Tiny rings on the inside of the shirt contain a hydrophilic polymer; the polymer expands when you sweat, hoovering up moisture and providing a cooling sensation thanks to the increased rate of evaporation. That, plus the fact that the F.K.T. II is covered with tiny dots of titanium dioxide (a key ingredient in sunblock) to reflect UVA/UVB rays, kept us from boiling over on 100°F days in the California desert.
The details The F.K.T. II has a half-length chest zip for venting and a drop-tail for full back coverage. Its polyester fabric survived a few run-ins with cacti, and one tester reports that she didn’t see any abrasion on the shirt despite wearing it under heavy pack straps for 100 days.
Trail cred “I was skeptical of the ‘magic cooling’ properties at first, but when the sun was blazing on the Pacific Crest Trail and I was working hard, I never overheated,” says our thru-hiking tester.
$75; m’s S-XXL, w’s XS-XL; Buy The Columbia F.K.T. II Short Sleeve Shirt Now