The Unicel C-5423 R is a compatible replacement for the following pool and spa water filter cartridges:
The Unicel C-5423 Comp. Pool & Spa Water Filter is a pool filter cartridge replacement constructed with 35 sq. ft. of pleated Reemay filter media for the reduction of contaminants in swimming pool and spa water. This compatible Unicel spa filter, also known as the Filbur FC-3623, measures 5 3/16" x 11 7/8" with a closed top style with loop and a 1 5/8" Open bottom style.