Two-Way Vent from Studor
The Maxi-Filtra, the newest product from Studor®, operates as a two-way vent that filters air in both directions. Its replaceable active carbon filter is designed to eliminate bad odors produced by the plumbing drainage system. For outside use only. Ideal for septic tanks, but can also be installed on existing open vent pipe and in systems in which air admittance valves are installed.