The Superfeet FLEXthin? Insole has been engineered to provide mild arch support and cushion to enhance the performance and feel of your athletic or casual shoes. Aerospring Foam ensures long-lasting cushion for activities including running, cycling, or heavy walking. It uses 3mm of all-around comfort and support. They work best as replacements for existing, removable insoles. Trim-to-fit for a fully customized size. Features odor-control technology for fresher performance. Flexible Heel cradle helps sit the foot in a better position.