Comes with neck made from galvanized steel to firstly connect the tube and then place the ceiling valve., Can be used for HVAC systems, air supply, exhaust and ventilation applications, placed on ceilings and walls., HVAC Round Ceiling Vent Diffuser, Disc Valve, Extract Grille, White Ventilation Ceiling Round Diffuser, Recommended for exhaust of greasy and damp air in damp areas such as toilets, bathrooms and kitchens.,