... Resistance Calcium filled polypropylene plastic Brown Air Intake,White air vent,Ventilation HoodAir Intake,air louver,ventilation outlet,air grilleThe gravity louvred vent commonly known ... be vented to atmosphere, while stopping cold air and pests entering the system when not in use.The louvreds are ... pls contact Deflcto .The step is as following : Brown Air Intake,White air vent,Ventilation Hood