This classic among Birkenstock’s flip flops has a fine, adjustable strap across the instep and around the toe. This flip flop with soft strap between the toes is very comfortable and secure on the foot. The Birkenstock Mayari Black is made of Birkoflor, a very soft material that reduces the chance of irritation and blisters. The orthopaedic foot bed of Birkenstock provides relief for the feet, knees and back. Birkenstock uses German shoe sizes. That is why you usually require a smaller size compared to other shoes or sandals.