Birkenstock Arizona Dark Brown Natural Oiled Leather Sandals, Unisex (43 M EU - 10-10.5 US Men) Synthetic sole They fit roomy for orthotic support: go down 1 size if you prefer a very tight fit without any wiggle room. Variations in the color or structure, discolorations, blemishes, scuffs and minor imperfections are inherent to the natural beauty of real leather. Unlike synthetic (man-made) materials; leather is a natural material, so every hide has unique characteristics; and as this product is made from many hides, the leather may show slight color and grain variation - this is natural. With regular use, as the leather fibres relax, comfort creases may form in areas that receive body contact. Leather will soften with wear (break-in period). Birkenstock footwear works by supporting your arches, reducing the strain on the muscles of the foot.