Membrane fabrics have been used for decades as a way to keep you warm while allowing a limited amount of moisture management. Our engineers have developed a fabric with all the benefits of a traditional membrane but with less than half the bulk - creating an extremely light weight water proof shield against the elements while packing down into a tiny storage space. Employing unparalleled moisture control and water resistance via 2 additional layers of micro-filament polyester, the lite-membrane is exclusive to 2XU.