The THS Filter is an NSF - approved 50 psi rated tank with flow rates up to 535 gallons per minute. the filter shell is manufactured from a unique and lasting composite laminate design that makes winding unnecessary. Paracote, a water based, environmentally- friendly coating, provides remarkable surface protection. Five sizes to 27 sq. ft. Manway in front for easy access and smaller footprint Manway with viewport available as option 6 in. flanged connections, 4 in. victaulic on the THS 3461 Optional manual, semi-automatic, and automatic backwash systems for one and two tank systems Two backwash controllers to choose from Influent manifold distribution to prevent clogging NSF approved from 5-20 gpm/sq. ft.