IPW Industries Inc. 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.