Dual Durometer For Medial-side Or Spur/fascia Relief And Maximum Comfort While Standing Walking Or Running medium-durometer Silicone In Main Body Efficiently Absorbs Impact And Recovers Quickly softer Silicone Blue Zone Area Provides Increased Comfort And Pain Relief optional Anti-microbial Cover Absorbs Odor Prevents Bacterial Growth And Allows Foot To Slide Easily Into The Shoe retains Shape -- Will Not Deform Or Degrade With Use washable And Reusable 1 Pair/package covered Large