The Ironman Thunder Pro Sock boasts the patented UltiMax Pro moisture control system to keep your feet cool, dry, and blister-free. X2O acrylic absorbs moisture, provides superior insulation, and contains Chitosan (which has natural antimicrobial properties). Dri-release technology further absorbs and repels moisture, dries super-fast, and remains extremely soft wash after wash. FreshGuard anti-odor technology keeps feet feeling fresh every time, while the heel tab prevents the sock from slipping. The sock features a lightweight, breathable mesh instep; cushioned sole; seamless toe closure; and a comfortable, foot-hugging fit. 56% Dri-release, 25% nylon, 17% X2O acrylic, 2% stretch polyester fabric blend. Made in the USA.