The UNICEL 4CH-21 R replaces the following pool and spa filters:
The Unicel 4CH-21 Comp. Pool Filter Cartridge measures 4 5/8" in diameter and 8" in length. This pool filter cartridge, also known as the Filbur FC-0121, has a Closed Crescent Handle top with a 1 1/2" MPT bottom. This Unicel pool filter has 19 square feet of media area for the reduction of contaminants in pool & spa water.