Aries (AF-20-3690) 20"x2.5" Activated Alumina FilterAries Filter Works 20"2. 5" Specialty Filtration Aries AF 20 3690 Activated Alumina Filter Specialty fluoride reduction filter using Resintech SIR 900 activated alumina media for well water and whole house applications requiring pH sensitive contaminant removal Made in USA FDA Materials 2500 Gallon Capacity WHY IT WORKS Activated Alumina Chemistry Resintech SIR 900 Media High capacity activated alumina specifically engineered for fluoride adsorption