The Lambro 4-In. Paint-Grade Steel Fresh Air Intake Vent with 11-In. Pipe is designed to introduce clean, fresh air into homes, particularly when gas appliances are in use or in modern, airtight constructions. The exhaust vent is for new and replacement installations over an existing opening. It features an opening containing a 1/4-in. wire mesh screen with a net-free area of 11 sq. in. When removing the screen, the net-free area of the unrestricted opening is now 20.5 sq. in. It is essential for all indoor gas appliances, such as gas heaters, gas fireplaces, gas water heaters, and gas dryers, to have a fresh air intake vent. Without this vent, these appliances depend on the oxygen available in the air, which can lead to the accumulation of carbon monoxide and carbon dioxide at unhealthy levels within the home. Constructed from 26-gauge paint-grade steel, this vent is built for durability and long-lasting performance. Before proceeding with installation, it is important to verify compliance with local building codes.