Nature 2 G CartridgeNature 2's G Cartridge gives pool owners already utilizing the G Model Systems to keep running without interruption, simply by replacing this cartridge element, which will maintain the purifying power of the G Model System for another 4 months. Containing natural minerals to compliment your chlorine, the G Cartridge will enable your pool to consume far less chlorine than normal yet still keep your pool healthy, but with a huge drop in side effects