The Ironman Endur Pro Low-Cut Sock boasts the UltiMax Pro moisture control system to keep your feet cool, dry, and blister-free. Ultra-light X2O acrylic provides superior insulation, moisture absorption and dissipation, and natural antimicrobial properties. Mesh air vents yield maximum breathability, while the seamless toe closure ensures long-wearing comfort. The Ironman Endur Pro Sock is made from a durable 62% stretch nylon, 36% X2O acrylic, 2% spandex fabric blend. Made in the USA.