KEEN Women Mt.Airy Low Lite Sock Y heel pockets for better fit, arch support, Seamless Anatomical Flex Fit System reduces bunching of material underneath foot and reinforced toe and heel for extra durability Action sock made with Dri-Release E.C.O. that has superior wicking and quick drying capabilities to reduce chances of blisters Dri Release E.C.O. is a blend of 85% recycled polyester and 15% organic cotton Air ventilation system surrounds foot for flow and quick release of heat, left and right specific fit, and ravel-free double welt top keeps socks up Limits the growth of odor through Fresh Guard