The GORE-TEX membrane is the heart of all GORE-TEX products. It contains over
1.4 billion microscopic pores per square cm (9 billion per inch). These pores
are 20,000 times smaller than a water droplet, but 700 times larger than a water vapor molecule, which makes the GORE-TEX membrane completely waterproof from the outside, while allowing perspira-tion to escape from the inside. In order to meet the specific needs of each end use,
W. L. Gore & Associates has developed different GORE-TEX® membranes and applies them as appropriate.