FROG @Ease Replacement SmartChlor Cartridge for use with Swim Spa FROG @Ease Floating System - Swim Spa Sanitizer System Supports Less Chlorine Use - 3 PackBrand: FROG Features: Swim Spa Replacement Cartridges: FROG SmartChlor Cartridges are designed for use with the FROG @ease Floating Sanitizing System; perfect for swim spas up to 3000 gallons Self Regulating Water Treatment: SmartChlor Cartridges require no maintenance or monitoring; each cartridge lasts 3 to 4 weeks depending on the size of your spa and how often it is used Cartridges Support Less Chlorine Use: SmartChlor is a patented chlorine