The OneFlow Plus Scale Reduction Replacement is to be used only as a replacement filter for the Watts Premier OneFlow Plus Whole House system. This salt-free scale reduction and water filtration system uses a commercially trusted, physical water treatment technology to keep scale from forming on pipes and reducing appliance life, along with a high-capacity water filter to remove foul tastes, odors, and sediments for better tasting tap water. A single, compact unit with dual cartridges replaces a space-consuming water softening system and water filtration system — using no salt, chemicals, and electricity. OneFlow Plus is an intelligent scale solution and is a great salt-free alternative to water softening (ion exchange) or scale sequestering devices. OneFlow Plus system is certified by the Water Quality Association (WQA) to NSF/ANSI Standard 372 for lead free. The carbon block used in the OFPRFC carbon filter is certified to NSF/ANSI 42. Watts Water Technologies OneFlow Anti Scale Media is certified by the Water Quality Association (WQA) to NSF/ANSI Standard 61.