Stack height of the midsole foam is 33 mm. EGO™ MAX foam. Midsole doesn't feel overly soft, it does offer a plush underfoot experience. Rocker shape of the midsole plays a pivotal role when it comes to the Via Olympus' underfoot feel. Encourage propulsion and efficient movement through the gait cycle. Original FootShape™ Fit upper is the roomiest of their three upper shapes. Upper limits the chance of your feet feeling pinched or squeezed during your run.