The Arizona's design is recognized a block away and around the world as the quintessential comfort shoe. The wide straps gently hold your feet allowing enough movement to flex and grip the toe bar and land upon the orthopedically designed footbed. This movement increases blood flow and strengthens the arches in your feet. The deep heel cup causes the flesh of your heels to move under the heel bones for natural added cushioning. Witness how the cork and latex combine to create a footbed that stands strong yet softens to accommodate the exact shape of your feet. Oiled leather can be recognized by its untreated surface. Birkenstock purposely does not treat surface grains and other characteristic features. Birkenstock uses sturdy leather with a thickness of 2.8 to 3.2 millimeters as upper material.