The size didn't fit, so it's a beautiful item worn only once. The size is 39, narrow, and black. The Madrid is the most enduring model from Birkenstock. It's a true classic. Appearing half a century ago as a "correction sandal," this minimalist one-strap sandal has already established its status as a fashion staple. The upper is made of Birko-Flor®, a skin-friendly and durable synthetic material.