Studor Maxi-Filtra 20700 Replacement Carbon Filter ONLYStudor Maxi-Filtra Gets Rid Of Smells And Odours From Septic TanksPractical Two-way Vent for External Drainage SystemsThe Studor Maxi-Filtra is a sturdy, active carbon vent designed specifically for outdoor applications to eliminate bad odours produced by the drainage system, and is ideal for use with septic tanks. Robust design means the Maxi-Filtra can be used externally, either vertically or horizontally, and can be installed in hard-to-reach places.The active carbon filter within the Studor Maxi-Filtra operates as a two-way vent, filtering air in both directions and absorbing the bad odours. The Studor Maxi-Filtra is packaged in a resilient exterior for longevity outside, together with an initial replaceable filter.The Studor Maxi-Filtra may be installed externally anywhere when the odour from existing vents present a problem, or when pipe vents are to be included in the drainage system of a new build:Septic tanksGrease separ.