Baleen Filters AK-3051 Pool Filter Replaces Unicel C-4975, Pleatco PRB75, Filbur FC-2395-Pool and Spa Filter Cartridges, 75 sq. ft. Media Area 75 sq ft, 4 15/16" OD, Open Hole: 2 1/8" Top, Open Hole: 2 1/8" Bottom, 20 1/8" Long, AK-3051 1 Year Warranty - Baleen Filters are made from Durable and Efficient USA Made Reemay Fabric - Washable Fabric Extends Your Filter's Life 75 sq. ft. EZ Twist Top Mount Skim Filter with Top Load Pressure for Custom Molded, Emerald, Hydro Pool, Nahani Spas by Maax, Serenity, replacement of Unicel C-4975, Pleatco PRB75 Baleen Filters Top: Open Hole: 2 1/8" Bottom: Open Hole: 2 1/8" Guaranteed Perfect Fit - Extremely Durable - Wash & Reuse - Most Energy Efficient - Withstands High Pressures & Temperatures