A good outdoor product has to be breathable enough for our body exhalations, so it keeps us warm during the activity and even afterwards.

Attributes of the material transfering the exhalations to the outer space is called permeability and it is being determined by g/m2/24 hours, that means how much wetness in g is going to be permeable on 1m

For the outdoor activities the permeability should be around 16g/m2 during 24 hours and more.