Arrived quickly and well packaged. Used it to cover outside airbricks on one side of house, as air flow was really bad when winds blew. Was going to fit airbrick cowl but they can reduce airflow by 80%. This was the compromise. Airflow important as it reduces dampness and condensation. Will be gradually covering airbricks and see if it has no adverse effect. (have 8 airbricks on a very small 2 bed semi)