The high-performance fan is installed directly under the roof outlet and provides sufficient negative pressure, even in the case of pipes that are up to three metres long. A gas-tight sanitary hose, a tried and tested product available in caravan accessory shops, is the easiest connection to install when retrofitting a roof ventilation system. The parts supplied are coordinated to fit a sewage pipe system available from specialist camping retailers  (this also applies to the SOG^®II model).