The ICON Technologies Holding Tank Vent Pipe Cover with aerodynamic design prevents odors from entering the RV by creating a vacuum while the vehicle is moving. The low, smooth profile keeps branches and tree limbs from catching and causing damage to the shroud and vent pipe. Inside it has a built-in aluminum screen to keep unwanted pests out. Fits vent pipes up to 3". Installs in minutes. Outer Dimensions: 7-1/2" x 6 -1/4" x 2 -1/4"Inner Dimensions: 5-1/4" x 4-3/4" Built-in aluminum screen inside keeps out unwanted pests Fits vent pipes up to 3"" Insalls in minutes | Icon Technologies Holding Tank Vent Pipe Cover Plumbing Stack Shroud in Black