PolySorb^®  Replacement Insoles provide the Technical Performance that helps you achieve more - more comfortably. They are proven to deliver the best combination of shock absorption and energy return, all while helping to reduce friction that causes blisters and calluses from forming. A contoured layer of lightweight polyurethane is bonded to closed-cell nitrogen-injected Spenco^®  material to provide outstanding cushioning and foot stability. Awarded the Seal of Acceptance by the American Podiatric Medical Association and Unconditionally Guaranteed for one full year.