Gore-Tex is a waterproof, breathable membrane that is often used in outdoor clothing. The membrane is laminated to high-performance textiles, such as nylon, polyester, and other synthetic fabrics. The membrane is made by stretching polytetrafluoroethylene. This results in a microporous structure. Because the microscopic pores are smaller than water droplets, but larger than water vapor molecules, sweat can escape from the body, while water is blocked out. Gore-Tex is the commercial name given to the product by its inventors. The generic name of the material is expanded PTFE (ePTFE).