Baleen: AK-90110, CAL P/N FIL11100211 Pleatco: PCAL60-F2M , Unicel: 5CH-752 , Filbur: FC-0202, Diameter: 5-3/16", Length: 16-1/8" Bottom 2 inch. This is a replacement filter cartridge for all Cal Spa hot tub models requiring a 75 Square foot enclosed filter. Baleen filter cartridges are made from Reemay, a spun bound filtration media that filters out even the smallest bacteria and debris, leaving you with pure, clear water. The AQUA FLUX™ Core is engineered to allow continuous and generous flow of water through the filter media.