The original Darrieus turbine has blades that are parallel to the axis of rotation, and that means that the loads in the blades are carried entirely by bending of the blades. That results in very high stresses, the re-design that we've done changes the blades so that they form this triangulated structure, and that's a very stiff and very strong structural form. And that means that the loads in the blades are principally carried by axial forces and that means that the stresses are much lower.