High-output activities require proper layering and temperature regulation. Stay ahead of the curve with the Phase AR Zip Neck LS and efficiently manage all of your moisture-inducing movements. Hybrid mapping of Phasic AR (in the body) and Phasic SL (in the underarm area) fabrics insulate you where you need it most while reducing weight and bulk in areas of articulation. The next-to-skin fit rapidly transfers moisture, keeping you cool when the skin-track steeply turns uphill, yet warm when you stop and wait for your buddies. If the temp heats up, zip down the neck and dump heat quickly while letting your chest hair flutter in the wind. The Phase AR Bottom is the perfect piece for colder weather layering, working equally well in the backcountry, at the resort, or all around.