APEC Water bundle of 2 Ultimate super capacity pre-filter sets is made in the US 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. A 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. Premium 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 with APEC Water Ultimate series RO systems and most other standard-size under-the-counter RO systems.