Unicel C-5397 Replacement Filter Cartridge for 80 Square Foot Rec Warehouse S2/G2 Spa, Rainbow, Waterway Diameter: 5 5/16-inch; length: 17 13/16-inch Top end cap: open, 2-1/8-inch inner diameter; bottom end cap: open, 2-1/8-inch inner diameter Pleat count: 223; filter media: 3-ounce reemay 2033; filter area: 80 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications