Castelli Fast Feet 4 TT Shoecover Seconds on the Clock Every second matters in a time trial, and the feet are one of the easiest places to lose time to aerodynamic drag. The Fast Feet 4 TT Shoecover addresses that directly. It was developed through extensive aero modeling of the foot and lower leg, cylinder testing to identify ideal shapes, and dynamic wind tunnel validation to confirm the results. A silicone-coated foot section smooths out the shoe's profile to clean up airflow, while a grooved leg section actively trips and detaches air as it wraps up the calf. The cut is high enough to do its job at race speed, and the gains are most pronounced at TT speeds where aero forces are working hardest against you. Features CFD and wind tunnel development designed through aero modeling, cylinder testing, and dynamic wind tunnel testing for maximum aerodynamic efficiency Silicone-coated foot section smooths the shoe's profile to reduce drag at the most exposed part of the foot Grooved leg section engineered surface texture trips and detaches airflow around the lower leg High calf cut extends coverage up to the calf to maximize aero gains where they matter most UCI-compliant construction designed for maximum aerodynamics within the rules of competition Shoe-size based fit sized to match your shoe for a precise, low-profile fit over the cleat area | Castelli | Fast Feet 4 Tt Shoecover | Size Small In White