Manufacturer Part Number: A630 Black 37; Birkenstocks unique insole structure reduces fatigue and supports foot health. By using a unique blend of natural cork and latex, you can wear it to fit the shape of the sole of your foot, and it comfortably supports your entire foot. The material and shape of the material is not easy to wear and will not lose the bottom surface so you can use it for a long time. The upper structure protects your feet from falling down knives.