Specially designed for use with the Manthorpe Alpha Vent for Slates; the Manthorpe Flexible Pipe (GRPA) provides an economical, quick and effective connection to standard 4" soil pipes and ventilation ducting systems. Free Airflow8,000mm2 Size455mm long The 455mm long pipe is made from flexible, low-density polyethylene and is supplied with a worm drive band clamp for secure fitting. Each Manthorpe Flexipipe allows 8,000mm² of airflow and is supplied with its own metal screw clamp for simple fixing.