Castelli FAST FEET 4 Socks

For road racing or when you can't wear a  TT shoecover, this sock saves watts. 

Castelli's Fast Feet project — for maximum aerodynamics
Foot portion based on 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
Temperature: 10°C - 38°C / 50°F - 100°F
Fit: Race