Delta Clarifi™ Reverse Osmosis Replacement Pre-Filter CartridgeClarifi Reverse Osmosis uses high pressure to push water through the systems four layer reverse osmosis filter, in addition to the pre filter and carbon filter, to remove 90+ contaminants from your drinking water. Designed for easy DIY maintenance, the carbon and RO filters and optional remineralizer cartridge have a two year lifespan so you can quickly and easily replace them at the same time, and it takes less than a minute to replace each filter.