Unicel C-7474 Replacement Filter Cartridge for 87.5 Square Foot American Quantum Diameter: 7-inch; length: 16 1/2-inch Top end cap: open, 3 0/0-inch inner diameter; bottom end cap: open, 3 0/0-inch inner diameter Pleat count: 225; filter media: 4-ounce reemay 2040; filter area: 87.5 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications