BIRKENSTOCK Madrid Big Buckle: EVA Warranty BIRKENSTOCK Damesschoenen Birkenstock Madrid Big Buckle EVA Black (1029635) Footshop. This is a new and modern interpretation of the BIRKENSTOCK classic Madrid. This version features their popular Big Buckle made from a stainless synthetic material and makes an impression with its durability and minimalist design. Modeled on the cork sandal, it is made from the ultra lightweight and highly flexible synthetic material EVA. The high quality, odor neutral EVA has been tested for harmful substances and combines numerous positive attributes: it is very light, highly elastic, shock absorbent, water resistant, and skin friendly. Anatomically shaped BIRKENSTOCK footbed made from EVA Upper, footbed, lining & sole: a single piece of EVA Water resistant, washable, ultra lightweight Medium Narrow width