Hydronix EC-4520W White Empty Water Filter Cartridge Durable Construction for Pre Post, Fits Standard Housings 4.5 x 20;

Empty Refillable Cartridges for Water Treatment Systems Filter Cartridge Model Number: C-C4220-EP For Filter Housing: 20" Big Blue Maximum Flow: 20 GPM Our empty refillable filter cartridges fit into a variety standard filter housing sizes. These cartridges can be filled with your filtration media of choice in order to create a filter cartridge that is custom to your specific needs. These cartridges come standard with built-in pre and post filters to keep the media from being washed out of the filter cartridge.