Outer Diameter: 7-1/4" Length: 21 5/8" Top Style: 2-15/16" Open; Bottom Style: 2-15/16" Open; Media: 100 SF Compatible with Filbur FC-6320, Unicel C-7302, Pleatco POX100, and Advantage Electric ELE-100 Hot Tub Spa Filters. SpiroPure pool and spa filter cartridges offer long-lasting, durable filter media with high dirt holding capacity for clear, sparkling water in your pool or hot tub spa. A strong inner core means increased strength without hindering water flow or filtration performance. Easy to install, durable filter cartridges that allow for high filtration performance and efficiency SpiroPure SP-PS-6320 Hottub Spa Pool Filter Replacement Cartridge. Easy to install, durable filter cartridges that allow for high filtration performance and efficiency.