AQUALUTIO AL-1117 premium quality 10" x 2.5" replacement pre-filter set extends the lifespan of your reverse osmosis membrane with the most innovated filtering technology. The 1st stage high-quality multi-layer sediment filter helps reduce clogs and minimize pressure loss. With GAC loose carbon filter being at the 2nd stage, it traps residual sediments in the water filtration process so that the 3rd stage CTO filter will not get clogged easily. The GAC filter also uses high-quality coconut shell carbon and 1.5 mm tiny pore carbon particles for maximum filtration efficiency and filter life. The 3rd stage CTO carbon block filter is made of bonded powered activated carbon filter media wrapped in a polyolefin pre-filter with polyethylene outer netting, and removes chlorine chemicals, tastes and odors effectively. What?s Included? 1 x 5 Micron 10" Sediment Filter (1st Stage, ): Removes dirt, rust, sand, and other particles. Replace approximately every 6 months. 1 x 5 Micron 10" Granular Activated Carbon (GAC) Filter (2nd Stage,): Absorbs chlorine, halide, organic contaminants, odors, and other impurities that contribute to bad tastes and odors. Replace approximately every 6 months. 1 x 5 Micron 10" CTO Carbon Block Filter (3rd Stage,): Further removes any remaining chlorine, tastes, and odors. Replace approximately every 6 months. Note: This filter set is designed to be a 6-month replacement pre-filter pack. It does not come with an RO membrane, as the membrane only need to be changed every 1-2 years. The F3 pre-filter set also fits counter top and undersink water filters with standard 10-inch housings.