This Replacement filter cartridge comes with the technical specifications as Filbur# FC-3930, Pleatco # PWK40, Unicel # C-6600, OEM # 31115. It is a great quality filter cartridge can handle a top load of 45 sq ft . This state of the art 45 SQ. FT. Hot Springs Spas, Hot Spot, Tiger River, Watkins Mfg filter With 3" open holes both at top as well as bottom is of unmatched quality. It is 11 7/8" inch long and 6 3/8" wide and provides you dust, sand and worm free clean and clear water solution for your pools and spas.