FG15B-KS 10" x 4.5" compound filter is designed to remove chlorine, lead, iron, mercury, hydrogen sulfide, chloride, chloramines, herbicides, odors, and other contaminants. Teaming up with carbon filters like iSpring FC15B, this filter removes the unpleasant taste or odor left in chlorinated water. They also tackle problems like turbidity, cloudiness, colors, bad taste, and odors like hydrogen sulfide that smell like rotten eggs. Official 1st stage replacement filter cartridge for iSpring direct connect Point-of-Use(POU) under sink water filtration system US21B. Fits standard 10" under-counter or whole house water filtration systems. Individually sealed for freshness. Based on the contaminant levels in source water and your water use, we suggest that you change your filters every 8-12 months for ideal filtration performance. Hassle-free filter cartridge replacement is a breeze! Please be noted that the system for which this filter works is NOT designed to reduce Total Dissolved Solids(TDS) removal and instead keeps minerals in your water. If you are interested in a filter that significantly reduces TDS, please consider our iSpring Reverse Osmosis (RO) systems RCC7 series or tankless RO500. We offer tech and CS support via phone and email from Atlanta, GA. Contact our responsive and professional team for product selection to suit your water filtration needs and after-sale support to maximize your user experience. Now, and years to come, we will be right here and ready to help.