Unicel 5CH-402 Replacement Filter Cartridge for 40 Square Foot Del Sol Spas Diameter: 5 3/16-inch; length: 10 3/4-inch Top end cap: bar handle, 0-inch inner diameter; bottom end cap: 2-inch male thread/mpt, 0-inch inner diameter Pleat count: 204; filter media: 3-ounce reemay 2033; filter area: 40 square feet Get more efficient filtration and better water clarity with Unicel filters Longer time between cleanings; meets oem specifications