The Pentek WS-20BB Water Softener Filter Cartridges contain FDA Grade Softener Resin. The Pentek WS-20BB water filters provide softened water in a convenient cartridge-style design. The Pentek WS20BB softening cartridges utilize a bed of sodium form cation resin beads to reduce hardness and scale deposits. Convenient and space-saving design means that softened water can be provided easily and cost-effectively at the exact point of need. NOTE: For drinking water applications do not use where the water is microbiologically unsafe or with water of unknown quality without adequate disinfection before or after the system. Also branded under Pentek Ametek Culligan Kleen Plus Plymouth Products Pentair American Plumber and USFilter.