Home Master CFF25-10 Jr F2 Replacement Water Filter, Activated Alumina/GAC Fluoride Filter, Purple Updated purple cartridge fits only one way, holds latest activated alumina media to purify better over a broader pH range Replacement filter for Tap Master Jr F2, Home Master Jr F2 Exceptional filtration: reduces Fluoride, Chlorine, and Chemicals Change the filter every 3 months or 500-Gallon depending on the hardness of your water