This refrigerator water filter features a PUR® Water Filtration System and can be used in top-freezer refrigerators with filter access in the base grille. Simply turn the filter 1/4 turn to remove and replace. While retaining beneficial fluoride, this filter is NSF® Certified to remove/reduce chlorine taste & odor, particulates, lead, mercury, cysts and 8 additional contaminants. The contaminants or other substances removed or reduced by this water filter are not necessarily in all users' water. For freshest water and optimal performance, replace water filter every 6 months.