The Sierra vent filter absorbs holding tank vent odors and keeps the surrounding air clean and pleasant. The vent filter eliminates the need for any holding tank chemicals.• Dimensions: 18.27" D x 2-15/16" H x 2-15/16" W With 5/8 Inch/ 3/4 Inch/ 1 Inch Inside Diameter Hose Fittings Plastic | Sierra Vent Filter for Holding Tanks