See link: https://www.rei.com/product/219294/teva-outflow-universal-water-shoes-mens Quick-dry mesh uppers are made from 30% recycled polyester and are backed by the Teva Universal Strapping System 100% recycled polyester microfiber linings provide a soft feel against your skin Stretch fit collars have hook-and-loop closures that allow you to get the shoes on and off quickly and get the fit just right 15% recycled EVA topsoles cushion your feet and provide a springy feel Outsoles contains 30% recycled Spider rubber, a high performance rubber compound that provides excellent grip Treated with Life Naturals, a responsibly sourced peppermint-based antimicrobial that fights the growth of odor-causing bacteria