4 housings of 20 Inch bb big blue filter with pressure release button and pressure gauge hole and plug , 1 Inch NPT. We beat the completion with Our High Quality Products This is not a low-priced Made in China Big Blue Housings that you can compare our product with some other advertised systems. Double O Ring 20 inch Big Blue inch. 1 inch inlet and outlet ports. Pressure release valve PLUS built in PLUS PRESSURE GAUGE HOLE + Plug in case you would like to use it without gauge. Accepts 20 inch x 4.5 inch diameter cartridges. Maximum Pressure: 90 psi. The item “4 Pack- 20 x 4.5 Big Blue BB Whole House Water Filter Housing pressure release” is in sale since Tuesday, November 5, 2019. This item is in the category “Home & Garden\Kitchen, Dining & Bar\Small Kitchen Appliances\Water Purification\Water Filters”. The seller is “max.water.usa” and is located in Tonawanda, New York. This item can be shipped to United States.