Arc'teryx Rho AR Zip Neck Men's Polartec Power Stretch - 90% Polyester, 10% Elastane 3" high 12" wide RHO AR ZIP NECK - Excellent midlayer for aerobic activities or expedition weight insulation for cold winter sports. Form fitting versions for men and women feature Polartec Power Stretch, which wicks moisture and prevents constriction. ALL ROUND - High performance weather protection and materials, emphasizing versatility for multiple activities. ARC'ESSENTIALS - Versatile high performance designs for diverse activities and conditions. POLARTEC - Synthetic fleece textiles with stretch, warmth and air permeable properties. Offers durability. RHO - Thermally efficient base layer with excellent moisture management properties. Has stretch comfort.