Use this plumbing vent to keep your RV smelling clean and fresh. If you have problems with sewage odors building up and nothing you do seems to help then this may be the solution. Simply remove your existing vent and bolt the Vac-U-Jet down in its place, its straight flow through design creates a jet of air that pulls out the odors from your sewage system. This roof vent greatly helps to eliminate odors from holding tanks and toilets while traveling. Instructions included. Fits most vent pipes. White in color. Dimensions: 3-3/4 inch H with a 5-1/2 inch base in diameter. 1 per package