FROG 01-14-3258 at ease SmartChlor Cartridge 3 Pack - This SmartChlor Cartridge 3 Pack is for use with the FROG at ease in-line system. Simply open the cap on your hot tub, snap in the conveniently adjustable cartridges and enjoy weeks of cleaner, clearer and softer water. SmartChlor technology self-regulates for continuous crystal clear water and uses up to 75% less chlorine.