Birkenstock's classic two-strap sandal done entirely in lightweight rubber. An elevated flip flop alternative. In Men's Sizes only. Also available in Khaki and Black. -100% EVA. Birkenstock footwear is created using premium, long-lasting materials including tear-resistant Birko-Flor, flexible, shock-absorbent EVA soles, and sturdy cork and latex, resulting in a shoe designed offer maximum support. Over time, the Birkenstock sandal will yield to the characteristics of the individual’s foot. In essence, it’s a shoe that, like the brand, only gets better with age.