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.