Manthorpe Telescopic Underfloor Vents with Extensions are designed to provide a clear airflow passage to the void underneath a suspended floor. This telescopic vent, part number G960, offers 6,600mm² of airflow. The telescopic feature allows for adjustment between 3 and 7 brick courses. It includes a special grille to prevent vermin entry and meets NHBC requirements for condensation control in buildings. Extension sleeves and other fittings are available separately. This product is compliant with BRE Digest 17, BRE Digest 262, Building Regulations C4, NHBC Standards 5.2, and BS 5250:2011 Control of Condensation in Building.