iSpring FT15 5th Stage Inline Post Carbon Filter Replacement Cartridge, White High-quality 10" x 2" Post Carbon Filter replacement cartridge. Used as the 5th stage on iSpring RO systems. It can also be used for refrigerators, ice makers, coffee machines, water coolers and more. Removes chlorine, tastes, and odors to improve the quality of your drinking water. Individually wrapped to preserve freshness. 1/4" connections. Depending on your water usage and quality, it should be replaced about every 12 months.