This sail of the pole is important as it reinforces the load of the most concentrated portion of energy into the pole while it bends. And this controls the stiffness along with other factors; mandrel size, body wrap sizes, and wrap lengths.
It is important to have a balance of sail, body wrap, and Hoop wrap in a pole for the maximum smoothness of the ride! As the pole increases in stiffness one may shift towards a more dominant Body Wrap to increase return. Some companies cut corners and they use the same sail configuration to save labor, It is important that this cutting corners method does give you a faster-returning pole, but can your athletes catch the ride? If not the method is wasted with a pole that returns faster than a vaulter can manage.