Birkenstock's classic single-strap slide done entirely in lightweight rubber. An elevated Flip Flop alternative. Women's sizes only. Also available in Red, Yellow, Navy and Black. -100% EVA. Birkenstock footwear is created using premium, long-lasting materials, resulting in a shoe designed offer maximum durability and 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.