Unicel C-8499 Replacement Filter Cartridge for 100 Square Foot Astral 2510 Ce Terra Diameter: 8 15/16-inch; length: 19 11/16-inch Top end cap: open, 3-3/4-inch inner diameter; bottom end cap: open, 3-3/4-inch inner diameter Pleat count: 168; filter media: 4-ounce reemay 2040; filter area: 100 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications