Recommended by doctors and pedorthists world wide. The orthotic NB 425 insole is tri-density with a molded Pedic™ core to support the arch and provide maximum comfort. The NB 425 has a posted rearfoot to control pronation and recommended for flat and low arch feet; a supported forefoot for those seeking metatarsal support to comfort ball-of-foot condition. Features include a top cover made with X-Static®, a fiber made from pure silver for improved performance.