Manthorpe Double Roman In-line Roof Tile Vent - Grey Properties Free airflow: 10000mm2. Length: 328mm. Width: 418mm. Top material: uPVC. Base material: polypropylene. Designed for use with: Marley, Redland, Sandtoft and Russell Double Roman, and Lagan Double Roll interlocking tiles. Features • In-line and discreet low profile design. • 4mm louvred flyscreen grille. • Integral sidelock clip to ensure secure fit. • Range of colours available. • Profiles suit top all top tile manufacturers. • Fully independently wind tunnel tested. • Base outlet feeds directly into roof space. • Adaptor available for mechanical extraction. • Suitable for use down to a 20° roof pitch. The Manthorpe Double Roman in-line tile ventilator is designed to provide a quick and simple solution to the problems of roofspace ventilation and mechanical extraction / soil stack termination through a Double Roman tiled roof. The profile vent is designed to replace a single tile and maintain an unbroken appearance to the roofline whether used at high or low level. The tortured path through the 4mm louvred grill and internal weathering geometry is designed to maintain a 10k mm² of airflow whilst channelling any water ingress out of the vent and on to the roof covering.