SockGuy's SGX™ socks are designed with the elite athlete in mind and features our exclusive Elite Performance Formula, a blend of polypropylene, nylon and spandex. The new SGX™ sock line provides a compression fit, performance ribbing, enhanced ventilation and a reduced friction profile. These socks feel great, look great, and with SockGuy's signature Stretch-to-Fit sizing and reinforced toe & heel, SGX™ socks perform like no other. Guaranteed to be the most comfortable performance socks you'll ever wear. Our SGX socks features: Compression ribbing cuff helps prevent fatigue by increasing blood flow. Mesh upper for maximum airflow ventilation. Snug arch support hugs foot for maximum comfort and virtually zero-slip. Streamlined friction-free sole: go longer and play harder with no pain. Seamless Toe. Sizing S/M L/XL Men (UK) 4.5-8.5 8.5-12.5 Men (US) 5-9 9-13 Women (UK) 4-7 7-12 Women (US) 6-10 10-14 Euro 37-42 43-48