Unicel C-8327 Replacement Filter Cartridge for 125 Square Foot Sundance Spas Diameter: 8 7/16-inch; length: 19-inch Top end cap: 1-1/2-inch male slip fitting, 0-inch inner diameter; bottom end cap: open with beveled edge, 2-1/2-inch inner diameter Pleat count: 199; filter media: 3-ounce reemay 2033; filter area: 125 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications