Review on Studor 20297 Maxi Filtra Admittance Valve by Andre Belitz

For ventilation of a septic tank, odorless. Not sure how long the filters will last but they will probably be replaced before the recommended 2 year period but the price for a pack of 20 filters (Studor 20700) is very reasonable. Fits perfectly in 4" Schedule 40 PVC pipe. No valve, just a filter. I see no need for a plug (Studor 20398) as it makes the vent look more obtrusive than it is and makes valve replacement difficult. Filter, and the unit is marked as UV-resistant