The PL-68 is much more than just an effluent filter. The housing can also be used as an inlet baffle (tee) or, with any 4 in outlet septic tank filter. The housing is designed to accept Polylok's snap in gas deflector to deflect gas bubbles away from the tee and to keep the solids in the tank. The PL-68 is ideal for residential waste flows upto 800 gpd.