Unicel C-4970 Replacement Filter Cartridge for 75 Square Foot Waterway Plastics Diameter: 4 15/16-inch; length: 23 5/8-inch Top end cap: open, 2-1/8-inch inner diameter; bottom end cap: open, 2-1/8-inch inner diameter Pleat count: 178; filter media: 3-ounce reemay 2033; filter area: 75 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications