"Caroflow Two-Way Threaded roof outlets are designed for use at the intersection of horizontal and vertical surfaces, i.e. a balcony and parapet wall, and can be used to drain off vertically or horizontally with the aid of the appropriate Caroflow Threaded Adaptor. They are female parallel threaded to BS21:1985 and available in three sizes; 50mm, 75mm and 100mm. Caroflow Two-Way outlets are suitable for connection to, Screw Threaded Steel and Copper (Gunmetal only). By using the Caroflow Threaded Adaptor, the Two-Way outlets are also compatible with PVC, Aluminium and Cast Iron. "