This product is part of Timloc’s Underfloor Vent System. It is a horizontal front extension piece that has been designed to be used with the Telescopic Underfloor Ventilator. You should only attach the Airbrick to the slotted end of this extension. This extension fits between the upper opening at the front of the Telescopic Underfloor Ventilator and Timloc’s Plastic Airbrick. It provides an additional 115mm to the ventilator. The extension is used when you have a thicker brick course or larger wall cavity. It is for used on external walls that are more than 102.5mm thick but are less than 215mm in thickness. If you need an even larger extension, this product can be slotted together to create longer sections. Features & Benefits Does not restrict airflow through the main telescopic underfloor ventilator Purpose-made accessories eliminate the need for on site modifications Lightweight and easy to handle Durable and totally resistant to decay Robust material Product Specification Added Length: 115mm Colour: Black Quantity: 20