For road racing or when you can't wear a Fast Feet TT shoe cover, this sock saves watts.

Product Features:

• Castelli Fast Feet Project — for hot weather rides
• Part of the foot designed in the same way as the Rosso Corsa Castelli sock to guarantee your comfort in the shoe
• Polyurethane grip band at the top to keep the sock in place
• Upper part made of grooved Lycra® to reduce resistance to airflow