The Unicel C-5621 R is a pool and spa water filter cartridge that is the correct compatible replacement for the following filters:
The Unicel C-5621 Comp. Pool & Spa Water Filter has an outer diameter of 5 3/16 inches, with a length of 11 7/8 inches. This Unicel spa filter has a closed top with a crescent handle, and an open bottom with a diameter of 1 9/10 inches and with slots. This Unicel C-5621 filter contains 22 square feet of filter media.