Ubbink's UB19 Double Romans vent is a streamlined hooded unit to suit:
Redland, 50 Double Roman
Marley, Double Roman
Sandtoft, Double Roman
The UB19 unit has a free vent area of 22,000mm² and is available in 4 colours.
For the UB19 vent to be converted into a terminal for soil/mechanical ventilation add a felt sleeve and adaptor 50544180