Birkenstock Honolulu flip flops. EVA material. Size 38, equivalent to a US 7-7.5. See size chart for details. The BIRKENSTOCK Honolulu is a sporty thong sandal with embossed straps. Modeled on the cork sandal, this sandal is made from light, flexible and waterproof EVA. Anatomically shaped BIRKENSTOCK footbed made from EVA Upper/footbed lining/sole: a single piece of EVA Details: waterproof, washable, ultra lightweight “Made in Germany”