This Replacement filter cartridge has meets the technical specifications as Unicel # C-4605, Pleatco # PMS8, Filbur # FC-3810 and OEM # PMS-8. This 8 inch long and 4 5/16 inch wide filter cartridge can handle the top load of 8 square foot and is best fit for 8 SQ. FT. Muskin, Sears. It has open holes of 2 3/16 inch each both at the top as well as bottom. It is made of very high quality material and provides you complete protections from germs and sand in your pools and spas.