Arc'teryx Phase SL Crew LS Men's 100% Polyester Imported PHASE SL CREW LS - Designed for high-output activities, the mens Phase SL Crew is a silkweight performance baselayer that rapidly wicks moisture and stretches with the body. 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. SUPER LIGHT - Superlight materials and design, emphasizing light weight and packability over durablity.