The GORE-TEX membrane is a series of pores. Each pore is 20,000 times smaller than a drop of water , but quite large so that steam can pass through it. This creates a perfect membrane which keeps the inside of your clothes dry but at the same time allows moisture and sweat to pass through, effectively regulating your body temperature while maintaining comfort inside a jacket or trousers. GORE-TEX guarantees that you will remain dry and warm in all conditions for the entire life of your clothing.