40% Olefin, 36% X2O Acrylic, 20% Stretch Nylon, 4% Lycra Spandex. Year Round Weight Is Perfect For All Classes Of Hiking Footwear. Stays Up With No Sagging Or Bunching. Crew Length Is Proportioned To Size. Full Terry Cushioned 3X1 Mock Rib Leg. Abrasion Resistant Achilles Cradle. Terry Cushioned 3X1 Filet Stitch Instep. Cushioned Sole. Ultra Smooth Lin-Toe Closure.