The ZeroWater Filter Bottle Water Cooler Bottle replaces bottled water service so you: Save money, Do not need to schedule delivery of water, Do not need to store or lift heavy 5-gallon bottles. Unlike conventional gravity-fed water filters, ZeroWater's patented 5-stage ion-exchange filter delivers the only filtered water to measure absolute 000 on the TDS meter. Compare that to the levels you'll find in other filtered waters, most bottled waters and plain unfiltered tap water - all of which contain measurable amounts of dissolved substances. Meter readings for tap water average between 75 and 300. Conventional filtered water measures between 030-500, and bottle water between 000-350. The Bottle Filtration Syster Come with the following products: The unique two-chamber Bottle Filtration System with lid that fits any standard water cooler. The Filter Bottle comes with: Two ZF-201 filter cartridges that remove contaminants that cause water to have an unpleasant taste; and An independently made TDS Meter to give you peace of mind that your ZeroWater filter cartridges are working properly. It also lets you know when to replace the filters. When your water starts reading "006" it's time for a change.