Unicel C-7656 Replacement Filter Cartridge for 50 Square Foot Hayward CX500RE Diameter: 7-inch; length: 19 5/8-inch Top end cap: open with molded gasket, 3 0/0-inch inner diameter; bottom end cap: open with molded gasket, 3 0/0-inch inner diameter Pleat count: 108; filter media: 4-ounce reemay 2040; filter area: 50 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications