Holding Tank Vent Filter Dometic goes that extra mile so that you don't have to and reducing the use of chemicals is always our aim, especially in a marine environment.  The Dometic DVF vent filter ensures just that and is designed to absorb odors from a holding tank vent and keep the surrounding air clean and pleasant.  The vent filter eliminates the need for any holding tank chemicals since it is manufactured with superbly effective odor-absorbing filter material. Adapters for different vent hose sizes are included in the kit. Features: * No chemicals needed * Absorbs odors * Environmental awareness