In Stock Free delivery overnight with DPD. Polylok’s Poly-Air-6 is an activated carbon vent filter that will remove offensive odours such as Hydrogen Sulphide as they come out of the septic tank, treatment system, grease trap or sewage system ventilation pipes. Use the Poly-Air activated carbon vents to eliminate these unpleasant odours. Features & Benefits: Easy to install Cost effective Fits existing 150mm(6″ inch) piping No more offensive odours No more spoiled patio parties No more foul air drifting into open windows Contains 5lbs of activated carbon pellets in each cover Easy replacement of activated carbon