Fi'zi:k Arione Versus X Road Bike Saddle K:ium Rails - Performance Exclusive Nylon/carbon shell uses Wing Flex technology so the rear sides of the saddle lex downward as you pedal, giving you greater leg clearance, increased pedaling power and a custom fit. 20mm channel the length of the saddle provides pressure relief. Thigh Glides design uses a sueded cover with remarkably good grip and smooth stitching along the sides to guide you into a pedaling form that's easier and more comfortable Microtex fabric around the sueded area of the cover is durable, water-resistant and further enhances grip, even when wet K:ium rails are lighter, stronger than titanium and corrosion resistant