For road racing or when you can't wear a Fast Feet TT Shoe cover, this sock saves watts.
. Castelli's Fast Feet project - for riding in warm conditions
. The foot portion is based on the Castelli Rosso Corsa Sock for in-shoe comfort
. Polyurethane grip strip at top to keep sock in place
. Leg portion constructed with engineered grooved Lycra to help detach airflow