Unicel C-7375 Replacement Filter Cartridge for 75 Square Foot Caldara Spa, New Style Diameter: 7-inch; length: 14 3/4-inch Top end cap: semi-circular handle, 0-inch inner diameter; bottom end cap: open, 2 11/16-inch inner diameter Pleat count: 216; 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