it comes in different widths and lengts, and we have a couple of different brands.
In our case it's a nonwowen-textile and consists of 2 layers of polypropen laminated with polyeten. The lamination lets water vapor move through the textile , it's light 72 g/square meter and is kind if elastic - very easy to work with ( just cut an x a bit smaller in size than that vent hole and press the textile over it and use some tape to fix it), it's very difficult to tear - a very sharp knife is required. And it effectively stops the wind. Usually placed just utside of the insulation.
NB: code in Sweden talks about a vapor barrier on inside of insulation, but it's not enforced/requiered.