Made with 75% Ultra-wicking Micro Denier Acrylic, 15% Nylon, and 10% Spandex for exceptional comfort and strength. ALL of our socks feature our "Stretch-to-Fit" sizing system and our exclusive "Easy-fit" cuff for a PERFECT FIT every time on any foot. These features create superior softness and comfort and help eliminate blisters and hot spots. We also feature a double stitched heel & toe for added strength and durability. We deliver Superior Quality and High-Tech Comfort in every SockGuy sock we make. We guarantee it. Sizing: S/M: Men's 5-9, Women's 6-10, Euro 37-42, M/L: Men's 9-13, Women's 10-14, Euro 43-48