Uncovered Large 1 Pair Dual Durometer For Maximum Comfort While Standing Walking Or Running Medium-durometer Silicone In Main Body Efficiently Absorbs Impact And Recovers Quickly Softer Silicone Blue Zone Under Heel Center Maximizes Shock Absorption And Comfort At Point Of Impact Retains Shape - Will Not Deform Or Degrade With Use Optional Anti-microbial Cover Absorbs Odor Prevents Bacterial Growth And Allows Foot And Insert To Slide Easily Into The Shoe Washable And Reusable