The Unicel C-6640 R is a pool and spa water filter cartridge that is the correct compatible replacement for the following filters:
The Unicel C-6640 Comp. Spa Filter - Jacuzzi CF-40 has an outer diameter of 6 9/16 inches, with a length of 19 3/8 inches. This Unicel pool filter has an open top and bottom with both having diameters of 3 1/2 inches. This Unicel C-6640 filter contains 40 square feet of filter media.