It is very good material has important features such as long-term waterproofing ability, an excellent resistance to the most extreme temperatures and high resistance to wear and tear. The special microporous structure of the Gore-Tex fabric in expanded PTFE contains around 1.4 thousand million microscopic pores per square centimetre. These pores are approximately 20,000 times smaller than  a drop of water, but 700 times larger than a molecule of water vapour. So while water cannot penetrate the Gore-Tex membrane in liquid form, sweat (water vapour) can easily evaporate. This results is a completely waterproof barrier that means the boot can be used in all climates, guaranteeing maximum comfort and optimal breathability.