The Extreme GT 4 from Northwave has a Morph Carbon 12 AAS sole with full carbon insert in the pedal area and a stiffness index of 12.0. The exclusive Anatomical Arch Support® in TPU allows the shoe to adapt perfectly to the arch of the foot, making it the ideal sole for any foot. The double SLW3 twist closure is the only closure system with gradual loosening that allows a precise fit adjustment of the pressure. Fitted in two crucial areas, it guarantees comfort and performance. The Performance Regular footbed provides more support from the bottom. The Extreme GT 4 is NW Speedplay/Wahoo adapter compatible.The perforated upper ensures optimal ventilation and via the mesh insert, excess heat gets out on hot days.