Birkenstock Kids' Rio AS Sandal (Toddler/ Little Kid)Size Chart Every detail considered for kids. The Rio sandal is made smooth and durable in our signature material, designed for easy cleaning. Featuring a secure, hook and loop backstrap and an original contoured footbed that's been sized down just for them. Play the day away. Contoured cork latex footbed creates custom support with wear Birko Flor synthetic upper Suede footbed lining Flexible EVA sole Hook and loop backstrap, adjustable strap with