Comfortable Surface : Velvet material, sweat-absorption function to keep your feet dry and comfortable Air Cushion :Built-in shock absorption function to relieve foot pressure. Detachable :You can adjust the height by attaching or detaching the removable insert, allowing you to increase your height freely. Breathable : The bottom hole allows the air between insoles and shoes to circulate, helps to draw moisture away from your shoes, and keeps your shoes and feet dry and comfortable. Flexible :Different size lines at the bottom of the insoles allow you to cut the size freely according to your feet size. How to use ? Please check your shoes depth before order. We recommend people wear 1-layer (appro 1.4in) at the first time, then gradually increase to 2-layer(approx 2in) for comfortable use. How to install ? There are 3 big holes on the back of the insole, Simply aim the 2nd layer at the 1st layer holes.