RV10K large spigot for roof ventilation. Dimensions Ventilation area: 10,000mm2. Airflow resistance: N/A Roof pitch: 20 degree pitch. Water resistance: exceeds all relevant parts DoE partners in technology programme. Description An exceptionally discreet vent designed for use in slate roofs. The RV10K and RP10K Roofline Slate vent are available in two sizes: 600 x 300mm and 500 x 500mm. The 500 x 500mm unit positions the vent in the centre with a simulated joint line, so it blends into a roof of 500 x 250mm slates. Features Careful design ensures the slate roofline vent is virtually invisible from the ground. A box below the vent collects any water that enters it and ducts it back onto the roof.