The outsole is made of Thermo-plastic rubber, a special rubber mixture that is soft and gummy. It has been painted and brushed to give it the leather stack finish. It also includes a leather welt with heavy stitch, and has a rocker bottom for enhanced walking motion and less strain on the back. Removable "4D Technology" footbed with four different densities developed in Germany. Our exclusive footbed contains Carbon particles for odor absorption, anti-microbial, anti-fungus. This high-density recovery foam never flattens. It is built for lateral stability, arch support, shock absorption and metatarsal insert with soft cushioning to relieve pressure on toes. The most perfect footbed for women standing on their feet all day.