Unicel 6CH-940 Replacement Filter Cartridge for 45 Square Foot Top Load Diameter 6 Inches, Height 8-1/4 Inches Top end cap: semi-circular handle, 0-inch inner diameter; bottom end cap: injection molded 1-1/2-inch sae thread, 0-inch inner diameter Pleat count: 225; filter media: 3-ounce reemay 2033; filter area: 45 square feet Get more efficient filtration and better water clarity with Unicel filters. Longer time between cleanings; meets oem specifications Will replace Waterway Plastics 817-0050, Vita Spas PWW 50, Rec Warehouse 378902, Custom Molded Products 25252, Aber Hot Tubs (Canada) 03FIL1400