The gore-tex membrane has over 9 billion pores per square inch. It's these pores that give gore-tex fabric its waterproof, windproof, and breathable characteristics.
There are one, two and three layer (1L, 2L, 3L) membrane applications, which are often supplemented with other technologies. The more gore-tex layers in product, the more lasting is waterproof ability. This material is perfect for activities in nature. Often used as abbreviation "GTX".