Aero Race pro 20 Sock - Men'sCastelli set out to make an aero sock that doesnt compromise on the things that make a great sock. Working with expert Italian knitters and state of the art machinery, they created a structure that combines smooth and textured zones to control airflow and reduce drag without sacrificing comfort or fit. The result is a sock that stays up, feels great, and delivers aero performance equal to ribbed Lycra cuffs with the bonus of true everyday wearability.