Pelican Water PHS-5 5 GPM Water Heater Shield, 0.75", Black FDA-grade polypropylene filter housing features thicker walls for increased durability Double o-ring design for superior leak proofing High-quality pressure gauge monitors pressure loss indicating the need for a filter change Pressure relief button on the inlet side of the cap makes filter changes quick and easy 100% FDA grade polypropylene fibers are made for wide chemical compatibility