Unicel C-4316 Replacement Filter Cartridge for 16 Square Foot Splash Tub Diameter: 4 15/16-inch; length: 5 1/2-inch Top end cap: molded cone handle, 0-inch inner diameter; bottom end cap: open, 1 9/10-inch inner diameter Pleat count: 177; filter media: 3-ounce reemay 2033; filter area: 16 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications