To further enhance this model, ION added an exclusive 3D Curv Spine. The high contour provides optimal back support thanks to a larger area. Additionally, the design features controlled center stiffness with flexible side parts, resulting in a perfectly balanced support harness and freedom of movement. With a flex index of 8, it is one of the medium stiffness models in the ION range of harnesses and it turns out to be a true all-rounder. The Apex 8 is also  equipped with ION's special C_Bar and additional Kite_Knife on top.