The FROG® @ease® floating system* offers a self-regulating water care experience that is easier than ever. Enjoy fresh clean mineral water combined with SmartChlor® technology that uses up to 75% less chlorine, maintains chlorine at lower levels, and reduces the frequent need for hot tub maintenance. The floating ball even turns over when your SmartChlor cartridge needs to be replaced. Package includes 3 SmartChlor replacement cartridges for the floating system. Use this system in spas with a single filter or in other brand spas.