Unicel C-7466 Replacement Filter Cartridge for 65 Square Foot Sundance Spas Diameter: 7 1/2-inch; length: 14 3/4-inch Top end cap: castle, 0-inch inner diameter; bottom end cap: open, 2 5/8-inch inner diameter Pleat count: 164; filter media: 3-ounce reemay 2033; filter area: 65 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications