The original BIRKENSTOCK sandal. A strap, buckle and contoured cork sole are masterfully combined to create the Madrid. The upper is made of skin-friendly, wear-resistant Birko-Flor synthetic material. Anatomically shaped cork and latex footbed. Upper: Birko-Flor. Insole lining: suede. Sole: EVA. Details: single strap with individually adjustable metal buckle. Available in women's sizes. The trend this summer at Birkenstock is comfort! This orthopaedic mule with a buckled, adjustable strap has the famous anatomic shock absorbing sole. Say goodbye to sore feet! This item has a narrow fit.