GAURDIAN 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 Filtration Fabric infused with Microban antimicrobial product protection Replaces Pleatco PDM25P4, PTL18P4-4 | Unicel 4CH-21 | Filbur FC-0136, FC-0121 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) Guardian Filtration Products New in factory packaging