Big Blue filter housings offer the versatility to meet all of your large capacity filtration needs, including high-flow and heavy-sediment applications. The extra large housing allows for greater cartridge capacity, reducing the number of vessels required for high flow-rate applications. Large capacity housing suitable for high flow applications Pressure-relief/bleed button on inlet side of cap Accepts 4-1/2" diameter cartridges The high-flow polypropylene (HFPP) cap is available with 3/4", 1", and 1.5 NPT inlet and outlet ports. Big Blue housings are compatible with a broad range of chemicals. They accept a wide variety of 4-1/2" diameter cartridges in 20" lengths. Materials of Construction Housing: Polypropylene Cap: Polypropylene (HFPP) Button Assembly: 300-series Stainless Steel, Polypropylene and EPDM O-Ring: Buna-N Maximum Temperature: 100F (37.8C) Maximum Pressure: #20BB 90 psi (6.2 bar)