2-PK Frog Serene Mineral Replacement Cartridges for Hot Tubs for use only with Frog Serene in-Line and Floating device Systems for Spa up to 600 gallons, Quick and Easy Hot Tub cleaner, Brand New sealed cartridges as shown on actual pictures.

For use in FROG Serene Floating System or In-Line System with the Bromine Cartridge (sold separately);

EPA 53735-11