The upper dispenses with the standard midfoot saddle, allowing the suede and synthetic overlays to flow from heel to toe across the mesh underlay, for a speedy, streamlined look. While the evolved design marks one of the most dramatic changes from one generation model to the next that the 990 has ever seen, the greatest leap forward occurs on the inside. The addition of FuelCell midsole cushioning means that the evolution of the 990 can be felt as much as it can be seen.