UNPUMP by Clarks Unstructured Nappa leather upper with lambskin lining makes this flat incredibly soft and flexible for a luxurious feel Interior seams have been reduced and strategically placed to reduce friction and provide 360 degrees of superior comfort and fit Injection-molded EVA midsole makes this shoe lightweight with energy return Rubber pads on sole improves traction for increased security Ultra flex grooves eases the walking motion through enhanced flexibility and no break-in required Clarks unique patented Air Circulation System (ACS) is a climate control technology that allows warm moist air inside the shoe to escape and replaces it with ambient outside air. ACS keeps feet cool, fresh and comfortable all day Wait till you feel what youve been missing