Caldera Spa Frog Bromine Cartridge provides spa and hot tub owners utilizing the Spa Frog System with an easy way to introduce bromine sanitizer into their systems in a self-contained cartridge, eliminating the need for measuring and lasting 2-4 weeks. Bromine Cartridge kills bacteria, reduces lingering odors, and removes other contaminants while providing a more comfortable environment for bathers. This product is designed for use with Spa Frog floating and inline systems and provides your pool with everything it needs to run at optimal performance.