The L420 Series is the same as the L400 Series with an added heel post for rearfoot control.The L420 Sports Series provides superior cushioning and shock absorption for athletic and walking footwear. Includes a soft, Copper Guard top cover made from state-of-the-art copper fibers to help prevent bacteria, fungi and odor. An advanced Lynco arch support comfortably balances your feet and provides proper body alignment. Features a Pro-Shox center layer for comfort and shock attenuation and an AeroCel polyurethane core for support. and shape retention. Light-weight, resilient and provides unmatched support and stability.