Birkenstock Madrid Patent is the best selling single strap style sandal from Birkenstock. The Birkenstock Madrid Patent footbed is contoured into the shape of a healthy foot ensuring the correct bones bear the weight of the body and keep the spine and legs in alignment. With lipped edges and raised arches Birkenstock Madrid Patent supports the foot's natural shape and structure. The Birkenstock Madrid Patent deep heel cup keeps the foot's natural padding under the heel to provide stability. Birkenstock Madrid Patent toe bar ensures toes grip and flex, invigorating circulation, exercising the leg and helping to maintain balance.