Unicel C-5396 Replacement Filter Cartridge for 100 Square Foot Waterway, Coast Spas Diameter: 5 5/16-inch; length: 21 5/16-inch Top end cap: open, 2-1/8-inch inner diameter; bottom end cap: open, 2-1/8-inch inner diameter Pleat count: 222; filter media: 3-ounce reemay 2033; filter area: 100 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications