Cartridge 9307A is designed for the reduction of aesthetic chlorine, taste an odor, VOC (volatile organic compoounds), and MTBE (methyl tertiary butyl ether). This replacement part is for exclusively i the Kinetico Drinking Water System Plus Deluxe VX models and Purefecta Drinking Water Purifiers. Cartridge 9461A is designed for the reduction of sediment and chlorine during the prefiltration stage in Kinetico drinking water system Plus Deluxe VX and GX models, k2 by Kinetico drinking water systems, Purfecta drinking water purifier, Aquakinetic A200 ans K5 drinking water station. This cartridge should be replaced each time your system's MACguard Filter (postfilter) shuts down (around 500 Gallons of water), you should replace your prefilter and postfilter cartridge at least once per year.