This replacement filter cartridge replaces Unicel # C-4611, Pleatco # PC11-4, Filbur # FC-3730 and OEM # PC-11. This 11 inch long and 4 ¾ inch wide filter cartridge is the best fit for Coleco F-112,F-350,CR-11,DR-11. With its 1 ¼ inch open hole at the top and 2 7/16 inch hole at the bottom this filter cartridge provides clean and clear water for your spas. By installing this high quality filter cartridges you get complete protection from germs and sand.