Speedlight 3d carbon sole a full carbon sole the 3 carbon layers drastically reduce thickness while increasing stiffness with a stiffness index of 10 transfer of all your full power to the pedals is guaranteed the airflow system of inlet and outlet ports prevents overheating of the sole and therefore the foot itself srs slim ratchet systemsrs is northwaves new micro metric buckle closure system maximum closing precision minimised size and weight the mechanism follows the anatomic