Pool Filter Replaces Unicel UHD-SR135, Pleatco PSR135-4, Filbur FC-2560 Filter Cartridge for Swimming Pool and Spa Media Area 135 sq ft, 8 11/16" OD, Open Hole: 4 3/16" Top, Open Hole: 4 3/16" Bottom, 34 1/2" Long, AK-8021 1 Year Warranty - Baleen Filters are made from Durable and Efficient USA Made Reemay Fabric - Washable Fabric Extends Your Filter's Life 135 sq. ft. Sta-Rite Pro Filter, replacement of Unicel UHD-SR135, Pleatco PSR135-4 Baleen Filters Top: Open Hole: 4 3/16" Bottom: Open Hole: 4 3/16" Guaranteed Perfect Fit - Extremely Durable - Wash & Reuse - Most Energy Efficient - Withstands High Pressures & Temperatures