The Pentek 150235 20-inch Big Blue Whole House Water Filter System has the great versatility to meet all of your large capacity filtration needs. It is sized to handle the water for an entire household, even in areas where you need to filter a high flow of water and/or a heavy amount of sediment. The 1.25-inch internal port allows a greater volume of liquid to pass through the cap with more speed, while the built-in pressure release button in the cap makes it easier to loosen the sump when it's time to replace the filter. The Pentek 150235 accommodates a wide variety of filter cartridges. Simply purchase the 20-inch x 4.5-inch filter of your choice.