The Whole House Ventilation System from Vent-Axia is a single module that continuously ventilates the property. It can also be used to improve the indoor air quality. There are models to suit all property types and sizes. This 3-Room Fixing Kit should be used in conjunction with a Mechanical Extract Unit (Quotes 73594 or 83656). Specifications: Spigot dia: 102 or 125mm. Associated products: 73594 and 83656.