Navien’s chemical-free anti-scale water treatment accessory PeakFlow is an environmentally friendly and effective alternative to water softeners. It provides protection from scale formation on plumbing surfaces in appliances and hot-water systems. The preinstalled inlet ball valve on the 15 lb. (6.8 kg) single cartridge provides easy isolation shutoff and filter changes. Certified to NSF / ANSI Standard 42 and 61.