Check the listing for details. NEW! FROG @Ease Replacement SmartChlor Cartridge 3 Pack with 6 Pack of Maintain. Condition: New, Made in United States. Listed at 92.90 USD. The SmartChlor system maintains proper sanitizer levels automatically, while Maintain shock oxidizes contaminants after heavy spa use, keeping your hot tub water fresh between refills. The advancedSmartChlor technology continuously releases sanitizer only when needed, helping reduce chlorine usage while keeping yourhot tub water clean, clear, and comfortable.The SmartChlor system maintains proper sanitizer levels automatically, while Maintain shock oxidizes contaminants after heavy spa use, keeping your hot tub water fresh between refills. The advancedSmartChlor technology continuously releases sanitizer only when needed, helping reduce chlorine usage while keeping yourhot tub water clean, clear, and comfortable.