The 9-inch ML2-920 effluent filter cartridge from Bear Onsite enables septic gases to exit through the outlet pipe and allows air to come in, replacing the hydrogen sulfide gas and carbon monoxide with oxygen and nitrogen. It has horizontal and vertical screens with progressively smaller apertures, allowing polarization to take place. The size of the primary screen aperture also increases toward the top to open the flow path. Inward folding pleats in the self-cleaning primary screen allow solids to drop into the tank and prevent plugging during periods of little to no flow. Molded connections allow for use of an alarm system, while molded-in handle couplings assist in filter changing. It provides 165 linear feet of total filtration and 125 linear feet of 1/20-inch final filtration rated for 1,875 to 2,500 gpd of flow, depending on application. 877/653-4583; www.bearonsite.com.