These exhaust and intake hoods are molded from high impact plastic with UV inhibitors. They are fully assembled with aluminum pipe and are available in different styles from 3" to 6". Exhaust hoods come complete with back draft damper to prevent cold air from returning into the home. Fresh air intake hoods are available with molded screen to prevent birds and rodents from entering your vents. Ideal for use in clothes dryer, kitchen, bathroom exhaust and heat recovery ventilator applications. Available as replacement caps too.