The Master Flow 4 in. Goose Neck Vent in Black can be used to cover exhaust pipes extending through your roof or for attic ventilation. This vent is designed to be used on 4 in. round ducts. It's made of zinc-coated galvanized steel for durability and reliability. This vent features a heavy-duty screen which helps protect against small animals from entering your home through the vent. The black finish helps this vent blend into your home's rooftop.