20″ Big Blue and Big Black Heavy Duty 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. Sumps are available in  20″ lengths. The High-Flow Polypropylene (HFPP) cap is available with 1″  NPT inlet and outlet ports. The 1 internal port allows a greater volume of liquid to pass through the HFPP cap more rapidly. Big Blue and Big Black Housings are compatible with a broad range of chemicals and are available with or without a pressure relief button. They accept a wide variety of 4-1/2″ diameter cartridges.