Individually wrapped for freshness. 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. The 1st stage is a 5-micron multi-layer gradient polypropylene snow-white filter blocks sediment, sand, dust, rust and anything that causes turbidity. The 2nd stage is granular activated carbon absorbs unpleasant chlorine, tastes and odors, cloudiness and colors. The 3rd stage is CTO carbon block absorbs any residual chlorine, tastes and odors, plus compounding pre-filters' efficiency and protect RO membrane. The final stage is designed for absorbing any possible residual tastes and odors.