REI Co-op Merino 185 Long-Sleeve Half-Zip Base Layer Top - Women's small EUC Ultrafine 185 g merino wool offers a soft feel without any itchiness Made with 100% merino wool that naturally breathes, wicks away sweat, dries quickly and resists odors, making it an ideal multiday trip companion UPF 30 sun protection Half-zip front helps with venting; standing collar and chin guard for protection Flat seams and merrow stitch construction eliminate chafing Underarm gussets allow full range of movement Designed to hug the body for optimum performance Weight: 6.8 oz. (size Medium) Machine wash warm, gentle cycle, with wool wash product; do not twist or wring; remove promptly; do not bleach; tumble dry low; dry cleaning not recommended Made in a Fair Trade Certified™ factory, which promotes safe working conditions and sustainable livelihoods Field-tested on its own and as a base layer while hiking, running, rock climbing, cycling, skiing and camping in diverse climates across the U.S.