You can remove the smell of your septic tank vents using the Linear Wolverine Brand Activated Carbon FilterTM for septic vent odor control. It has a versatile linear filter design. It is available in 2 sizes. The LRF-25 come standard with a 4-inch inlet and holds 2.5 pounds of activated carbon. Each Linear Roof Filter is manufactured in the U.S.A. and is made of schedule 40 PVC. Schedule 80 and ABS models are available as special order. Each Linear Roof Filter is equipped with a drain plug and accepts our unique Saturation indicator to allow monitoring of the carbon bed so you change the carbon before the odor becomes noticeable. The LRF-25 vent filters comes complete with a rain cap.