The Fluoride Shield is one of the options for the #1 spot on the Athena. It will filter out Arsenic, Fluoride, and Chlorine. This filter is far better than any other filter for the removal of fluoride. Good for up to 500 gallons of filtered water.
Note: The AlkaViva water experts state that the Fluoride Shield filter is not for sediment and a separate sediment filter may be required to prevent clogging of the very fine Ultrawater filters. If you have a water sediment problem you are probably better off getting the external Fluoride Shield and then inside the ionizer use the standard UltraWater filter set (which has a sediment filter as part of the set).