These Arizona Birkenstock sandals have 2 straps that are adjustable to ensure they are a comfortable and secure fit. The upper material is made of birko flor which is gentle on the skin. The upper has been lined on the inside with a soft breathable layer of fleece and these sandals have flexible leather lining that is also gentle on the skin and adjusts to the contour of your feet. The footbed is made from natural cork and is insulating and cushioning. The EVA outsole is high quality, lightweight and elastic while providing cushioning.