Berkey PF-2™ Fluoride and Arsenic Reduction Filters are manufactured and assembled in the USA. Berkey PF-2™ Fluoride and Arsenic Reducing Elements adsorb the following undesirable elements found in drinking water: Fluoride: sodium fluoride, sodium fluorosilicate, fluorosilicic acid (aka hydrofluorosilicic acid) Arsenic: V and pre-oxidized Arsenic III Other residual heavy metal ions Made from safe, non-leaching #5 polypropylene, BPA free. Sold in sets of 2 Berkey PF-2™ Fluoride and Arsenic Reduction Elements are designed for use only with Black Berkey® Purification Elements Attach to the bottom of the Black Berkey® Purification Elements and sit in the lower chamber of the Berkey unit The number of Berkey PF-2™ elements in the lower chamber must match the number of Black Berkey® purification elements in the upper chamber; for example, 4 Black Berkey® purification elements would require 4 PF-2 filters Set of 2 Berkey PF-2™ elements to be replaced after 3785 liters of use Berkey PF-2™ Fluoride and Arsenic Reduction Elements are backed by a six-month warranty