Upgrade your shoes with Superfeet FLEXmax insoles. An excellent introduction to doctor-recommended Superfeet shape, the special flex design hugs your feet and cradles your heels to help your footwear, and you, feel great. Durable 5mm thick Aerospring™ comfort foam delivers heel-to-toe comfort, while the flexible heel cradle provides structure and stability, reducing stress on feet, ankles and knees. FLEXmax insoles fit best in roomy athletic footwear. Trim to fit your shoe size.