HEAVY DUTY FILTER HOUSING ideal for large-capacity, high flow applications. CLEAR SUMP HOUSING offers on-site examination of flow, cartridge life and performance. PRESSURE RELIEF BUTTON for easy cartridge replacement. COMPATIBLE WITH ANY 10″ x 4.5″ Big Blue or other heavy duty sediment or carbon filter cartridge. CONSTRUCTED of reinforced polypropylene (cap) and Lexan (sump).