Arc'teryx Phase AR Zip Neck LS Women's 100% Polyester 3" high 6" wide PHASE AR ZIP NECK LS - A midweight baselayer top for high output in cooler temperatures, the Phase AR Zip Neck is made from next generation Phasic AR. ARC'TERYX ESSENTIALS - Versatile high performance designs for diverse activities and conditions. PHASE - Quick dry base layer with excellent moisture management. For high output activities.