Baleen Filters 25 sq. ft. Pool Filter Replaces Unicel C-5601, Pleatco PJW23-4, Filbur FC-1330-Pool and Spa Filter Cartridges Model: AK-4021 Media Area 25 sq ft, 5 11/16" OD, Closed w/ string loop Top, Open Hole: 2 1/8" Bottom, 10 3/8" Long, AK-4021 1 Year Warranty - Baleen Filters are made from Durable and Efficient USA Made Reemay Fabric - Washable Fabric Extends Your Filter's Life 25 sq. ft. Front Load Filter for Jacuzzi Whirlpool Bath, replacement of Unicel C-5601, Pleatco PJW23-4 Baleen Filters Top: Closed w/ string loop Bottom: Open Hole: 2 1/8" Guaranteed Perfect Fit - Extremely Durable - Wash & Reuse - Most Energy Efficient - Withstands High Pressures & Temperatures