16 in. x 8 in. Automatic Foundation Vent in Black (10 Vents per Carton)Foundation Vents allow air to enter and exit the crawlspace. This airflow helps to remove heat and moisture. The crossflow of air helps protect against foundation problems. California residents see Prop 65 WARNINGS Heavy duty construction Premium bi metal coil Honeycomb grill 16 in. x 8 in. rough opening 50 sq. in. of net free area airflow each Opens and closes automatically Provides a functional way to vent the crawl space of the house Easy to