High-efficiency filtration: It can protect you from harmful spring and well water by effectively reducing fluoride and arsenic. â­�Please note that TDS level does not fully indicate the quality of the water and our filters DOES NOT lower TDS value.â­� Safe material: This filter uses granular activated carbon and activated alumina to improve the water taste and to ensure harmful substances will not leach back into water.Longer service life: To achieve optimum performance, we recommend you replace fluoride filter every 1,000 gallons per pair, which will vary based on water conditions.Perfect fit: Compatible with the Gravity Filtration System fluoride/arsenic replacement filter.Compatible models: Interchangeable with the Travel, Light, Big, Royal, Imperial and Crown series. This filter is not sourced or sponsored by original brand. The manufacturer"™s series name has been used for reference purposes only.