Stainless Round Louvered Vent - 4"This round louvered vent allows air in while keeping water out. Constructed of corrosion-resistant stamped 304 stainless steel. Installs with four #6 FH fasteners (not included). 4" vent area (0.88 in.2).Specifications:Outer Diameter (inch): 4"Hole Size (inch): 2-1/2"Circumference (inch): 3-5/8"Vent Area (inches squared): .88 in.2Fastener: #6 FHWeight: .07 lb. The Sea-Dog Stainless Round Louvered Vent is a durable and high-quality ventilation system designed for boats and other marine applications. It is made from high-quality stainless steel, which provides excellent resistance to corrosion and ensures that the vent will last for years to come. The vent features a round louvered design, which allows for maximum airflow while also keeping out debris and water. It is 4 inches in diameter, making it a versatile size that can be used in a variety of applications. The Sea-Dog Stainless Round Louvered Vent is easy to install and comes with all of the necessary hardware. It can be installed using screws or adhesive, depending on your preferences and the type of surface you are mounting it on. Overall, the Sea-Dog Stainless Round Louvered Vent is an excellent choice for anyone who needs a reliable and durable ventilation system for their boat or other marine application. Its high-quality construction, efficient design, and easy installation make it a valuable addition to any vessel.