Mephisto Heike Twist Silver has a sole unit is composed of 100% rubber with air injection, for added flexibility. The shock absorbent soles reduce foot, and leg strain. Cement construction for increased durability. Footbed is composed of a mixture of cork and latex, to provide maximum support, and shock absorbency. Wider straps than the classic Helen and a beautiful black and silver woven strap with oversized buckle.