Always want to take your Birkenstock for a swim? Now you can! These Gizeh thongs are made of 100% EVA, which is lightweight, flexible and shock-absorbing! Features 100% EVA synthetic Water, oil, and grease resistant Arch contours Fitting And Care Notes: The Gizeh EVA is only available in regular width, but people with narrower feet can usually wear this width as it is adjustable. They are quick to soften up but may rub a little bit on the foot to begin with so it's best to wear them in gradually. Please avoid leaving these in direct sunlight or extreme heat as EVA can shrink. Please note that Birkenstock EVA sandals are not designed as an everyday street shoe. They are perfect for around the pool, at the beach or on the boat, though they are not designed for regular use on concrete or pavement and this will impact their longevity.