Hellion utilizes a lightweight, breathable, and durable asymmetrical upper built with Cordura thats designed to keep you riding farther and charging harder. The PerformFit Wrap from the BOA Fit System is designed to improve power transfer and efficiency while providing a micro-adjustable, precision fit you can adjust on the fly. The asymmetrical collar provides additional protection on the inside of the ankle and the molded EVA midsole gives your foot a stable and efficient pedaling platform.