Aqua Kleen AK-4005 Unicel Replacement Filter Cartridge for Swimming Pool and Spa 50 sq. ft., 5 3/16" OD, Closed Top, Open Hole: 1 5/8" Bottom, 14 1/8" Long, AK-4005 Exact Fit for Unicel: C-5346 Exact Fit for Pleatco: PPM50TC Exact Fit for Filbur: FC-3638 Guaranteed Perfect Fit - Extremely Durable - Wash & Reuse - Most Energy Efficient - Withstands High Pressures & Temperatures