Improved sail control at higher wind speeds. Kai Hopf relied on WARP F2007 to design the TT.TOP II. The concave shape is slightly reduced, which improves the tension and allows for a more effective, three-dimensional twist at the head, meaning that the top twists not only horizontally but also vertically under strong winds. This virtually neutralizes gusts, keeps the rig steady in the rider's hand, and allows the sail to be used in a much larger range of winds.