This replacement filter cartridge has the technical specifications as Unicel # C-4431, Filbur # FC-3078 and OEM # C4431. It is 10 3/8 inch length and 4 15/16 inch width, this filter cartridge can handle the top load of 30 square foot while it is the best fit for skim filter, Lifestyle, Discovery Spas, Grecian Spas. This filter cartridge has 2 1/8 inch open holes both at the top as well as bottom. By installing this filter you get complete protection from any debris in your pools and spas. Very easy to install this filter cartridge is made of high quality materials.