2 pak-filter FITS- PLEATCO PDM18P-4, PDM25P4 DREAM MAKER GATSBY SPA unicel 4CH-21, HOT TUB CARTRIDGE,filbur FC-0121, FC-0136 ANTIMICROBIAL MICROBAN PROTECTION AGAINST BACTERIA GROWTH Replaces Pleatco PDM25P-4, PTL18P4-4 | Unicel 4CH-21 | Filbur FC-0136, FC-0121 Guardian Filtration Products 4H8-158-02M New in factory packaging Diameter: 4-5/8',' Length: 8'', Top: Handle, Bottom: 1-1/2'' MPT Threaded Filter Area: 18 sq. ft., Filter Material: Reemay (4 oz/yard) Filtration Fabric infused with Microban antimicrobial product protection