Marquis Spas Signature Series hot tubs use this closed top threaded hot tub filter. They have also started using this cartridge in their new Celebrity Elite Series. Some lines of Cal-Spas and Coleman Spas have also used this cartridge. As we are a Marquis Spa dealer here in Massachusetts we label this as a Marquis Cartridge in our system, although it is a common filter used by many brands.
The Unicel cartridge cross reference number is 5ch-502 as shown in the product image.
The cartridges we carry are blue pleats with Microban Anti-microbrial protection.
We recommend changing your filters once per year if cleaned regularly once a month.
Dimensions are 12.5″ x 5″ with a 2″ threaded bottom opening.