The Hambleside Danelaw soffit and fascia product ranges provides roofspace ventilation at the lowest level of the roof line. All grille and mesh sizes are designed in accordance with the recommendations within BS5250. These vents help to avoid excessive airflow resistance and prevent the ingress of birds and large insects. HD 12000m Our over fascia vent provides a through-flow of ventilating air over the fascia board in both new build and refurbishment details.Conforming to standard flyscreen regulation requirements, this vents rounded front sections prevent blocking of airflow from overlapping underlay. Properties Airflow: 10,000mm2 airflow per metre.Length: 1m.Width: 33mm.Height: 19mm.Material: polypropylene.Colour: black.