Timely replacement of filter cartridges is essential for the water quality and lifespan of reverse osmosis system. There are 7 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 RCC7, RCC7P, RCC7U, and RCW5, 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 - guaranteed to perform and last for the best. Choose ISPRING genuine filter pack for the quality, value and your peace of mind.