Pool Filter Replaces Unicel C-5635, Pleatco PJ37-IN-4, Filbur FC-1437 Filter Media Area 37 sq ft, 5" OD, Open Hole: 2 3/8" Top, Open Hole: 2 3/8" Bottom, 13 5/16" Long, AK-4031 1 Year Warranty - Baleen Filters are made from Durable and Efficient USA Made Reemay Fabric - Washable Fabric Extends Your Filter's Life 37 sq. ft. In-Line Filter for Jacuzzi CFR-37, replacement of Unicel C-5635, Pleatco PJ37-IN-4 Baleen Filters Top: Open Hole: 2 3/8" Bottom: Open Hole: 2 3/8" Guaranteed Perfect Fit - Extremely Durable - Wash & Reuse - Most Energy Efficient - Withstands High Pressures & Temperatures