The Pulsar® 30056 25 lb 2.7" Infinity Blue Cal-Hypo Tabs are un-stabilized chlorine tablets that have 70.2% calcium hypochlorite. These caplets are made to prevent the growth of algae, harmful bacteria, and organic contaminants in your swimming pool, keeping your water safe and swimmable at any time. For use only with the Pulsar Infinity Feeder.