Castelli set out to make an aero sock that doesn’t 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.