The Pura 41407002 QCRO Quick Change Carbon Block Filter is the replacement carbon prefilter for the Pura QCRO and QCUF systems. It is a 5 micron carbon block and reduces chlorine, taste and odor to protect the membrane and give you better tasting drinking water. Reduces chlorine, taste and odor Micron Rating: 5 micron Filter Life: 2000 gallons Filter should be replaced every 6 months