Timely replacement of filter cartridges is essential for the water quality and lifespan of reverse osmosis system. There are 17 pieces of 2.5 in. x 10 in. (industrial Standard) filter cartridges included in this genuine ISPRING filter pack, make it the convenient 1 year supply for ISPRING RCC1UP, RCC7U, and most other reverse osmosis water filtration systems in the market that use Standard 2.5 in. x 10 in. cartridges. The same as ISPRING water filter systems, these filter cartridges have been tested by independent third-party to meet NSF/ANSI Standard for material safety, durability and filtration performance. Choose ISPRING genuine filter pack for the quality, value, and your peace of mind.