APEC Water Systems Water Systems Ultimate high capacity pre-filter set is made with high quality filtration components to protect and prolong the lifespan of your reverse osmosis system. Premium quality filter set lasts over 12 months for fewer filter change outs and high performance contaminant removal. These standard size filters are 10 in. and compatible with all standard size under counter RO systems. 1st Stage: High-Grade 10 in. high-capacity polypropylene sediment filter - removes dust, particles, and rust. 100% pure polypropylene depth filter with exceptional dirt-holding capacity translates to longer life and fewer change-outs than existing string-wound or resin-bonded filters. 2nd and 3rd Stage: Premium Extruded Carbon Block 10 in. - gets rid of unpleasant chlorine, tastes, odors, cloudiness and colors. Also removes VOCs and other common chemicals from the water. APEC Water Systems Water Systems extruded carbon block filters consist of activated carbon particles fused into a uniform block with enhanced adsorptive capacity and efficiency. Unlike granular activated carbon (GAC) filters, these extruded carbon block cartridges will not channel or bypass due to the extreme uniformity of their extruded activated carbon core. Compatible for APEC Water Systems Water Systems RO-45, RO-90, RO-PERM, RO-PUMP and all other standard size under counter reverse osmosis systems.