Replacement filters for ZeroWater Travel Bottle (model #ZB-030). Features ZeroWaters patented, 5-stage filter technology which is very effective at removing virtually all dissolved solids (TDS) from tap water so you can enjoy TDS-free, pure-tasting water. Each filter is built with a color change window which shows exactly when to replace the filter. Just unscrew the filter from the bottle"s lid and replace.