“I immediately felt cooler when I slipped this on,” says one tester who switched out of a sweaty, short-sleeve synthetic tee halfway through a sun-scorched hike in the Jordanian desert. The magical cooling sensation comes from Xylitol—the same minty ingredient found in many chewing gums—embedded in the 91 percent polyester/9 percent spandex fabric.
Xylitol is a sugar alcohol derived from birch trees. When it gets wet, it causes a heat-sapping chemical reaction, and ExOfficio uses a bonding agent to make the effect last through 40 wash cycles. “I’m a big-time sweater and notorious for getting lobster-baked in the sun,” says another staffer. “So this was a total game-changer for me. It wicks sweat superfast, and it’s cooler wearing this shirt than nothing at all.” The UPF 50+ fabric is light and stretchy with a comfortable—not clingy—fit that won’t raise eyebrows in town, though after a few days, your body odor might. “I wore this shirt for four days straight in Jordan,” says our gear editor. “I wish it smelled as minty as it felt.” Tip: When you hit a shady rest stop after sweating, you cool down really fast in this shirt, so have a midlayer handy. $75; 7.4 oz. (w’s M); m’s S-2XL, w’s XS-XL; exofficio.com