Glidevale RV Rafter Ventilators are designed for use with FV Fascia Ventilators and SV Soffit Ventilators to ensure a clear air path between the roof underlay and insulation at all types of eaves. Suitable for new build and refurbishment work.For use with low pitched roofs (below 15 degrees) and flat roofs and where ceiling line follows roof pitch. Also recommended for plastic based roofing felts. Offers 25mm airflow. Can be used with new buildings or exisiting buildings with new roof coverings. 600mm rafter spacings.Ariflow of 25,000mm2/m.Suits rafter centres of 400mm, 450mm & 600mm.Suitable for corbelled brickwork.