A claim made by the sellers of these 100% fake jackets is that they are 'breathable'. The fabric should be coated on one side with a breathable membrane. A good test is to boil the kettle, then pour the boiling water into a cup. Put the fabric of the jacket over the cup tightly and put a mirror over the fabric (around 2 -3" away). If the mirror show condensation then it is breathable. If it shows little or no condensation then it is cheap fabric.