Birkenstock Milano Essentials Sandals. The Birkenstock Milano - a classic back-strap sandal with functional style for kids. Modeled on the cork original, this back-strap sandal is made from ultra lightweight and highly flexible EVA. These sandals are shock absorbing, waterproof, and skin-friendly. Wear them at the beach, in the backyard, or by the pool. Sandals for all-day play! Three straps, each with an individually adjustable resin pin buckle. Backstrap. Waterproof. Ultra lightweight. Imported.