Don't let this jacket's name fool you. Its rare combination of low weight, bomber durability, and excellent breathability makes it far more than a mere running shell. "It's an all-star on any high-exertion outing–fast dayhikes, peakbagging, mountain biking, and, of course, trail running–in drizzly weather," said one Colorado tester.
After summiting Mt. Neba and racing back to the trailhead through afternoon storms, he said, "We were moving fast, and I never felt clammy." Credit the very breathable eVent membrane and large swaths of light, stretchy, water-resistant nylon along the sides, pits, and inner arms. There's no hood (this keeps you cooler and reduces weight), so pair it with a cap and consider the Airflyte best for working hard on day trips. $169; men's and women's S-XXL; 11 oz.; rei.com.