This isn't just any shoe cover. The design of the Castelli Aero Race Shoe Covers MR began last season at the Tour de France's prologue. Using technical fabrics and a sleek design, Castelli has created possibly the most aerodynamic shoe cover on the market. Using CFD computer modeling, Castelli was able to develop a shoe cover that allows air to flow over its surfaces, giving you every split second advantage over your competition. Lycra was placed on the front where the wind hits the shoe first, and a textured mesh was added to smooth air separation. The shoe cover is secured with a full length rear zipper. The Castelli Aero Race Shoe Covers MR come in sizes Small through XX Large and in the colors Black and White.