Timely replacement of filter cartridges is essential for the water quality and lifespan of the reverse osmosis system. There are 19 pieces of industrial standard filter cartridges included in this genuine iSpring filter pack, making it the convenient 1 year supply for iSpring RCC7AK, RCC7PAK, and most other reverse osmosis water filtration systems in the market. The same as iSpring water filter systems, these filter cartridges have been tested by an independent third party to meet NSF/ANSI standards for material safety, durability, and filtration performance - guaranteed to perform and last for the best. Choose the iSpring genuine filter pack for quality, value, and peace of mind.