There are actually two layers of foam in this windscreen - a coarse and hard, open-cell layer covered by a dense and soft open-cell layer. This arrangement creates the space of still air around the mic capsule that a blimp implements, increasing effectiveness.
It can be used outdoors in light breezes with good results. In stronger winds a proper blimp with fake fur will be needed.
The price is probably fair given the decent quality. Certainly the price seems much more reasonable than that demanded by a neighbouring German manufacturer of premium microphones for similar accessories!