NRG Air Carbon reinforced sole with a stiffness index of 8.0 and 5 ventilation openings for perfect air circulation. SPD pedal compatible (mounting plate not included). The seamless unibody construction of the upper material reduces pressure points. 4 breathable mesh inserts and pores throughout the surface ensure optimal ventilation. SLW3 rotary closure with extra Velcro strap: the only rotary closure that allows for step-by-step loosening or complete opening at the push of a button.