DuoClear® W28000B Single Mineral Cartridge is used with the DuoClear® in ground pool system. The Nature2® DuoClear® combines the sanitizing effects and water clarity of Nature2® mineral technology with the convenience of automatic chlorine generation from Clearwater salt technology. The Nature2® mineral bed technology uses silver and copper to combat bacteria. The saltwater chlorinator component automatically produces low levels of chlorine, eliminating the need to buy and store chlorine. Together these two technologies create a low maintenance, low cost system for pool sanitizing, with water that feels soft and silky.