Brominating Tablets are a spa and hot tub sanitizer. Compressed 1" bromine tablets provide long lasting sanitizing protection. This is a hard-working product that will kill and control bacteria - resulting in water that's a pleasure to soak in. With 4.5 pounds of these powerful bromine tablets, your spa or hot tub will stay crystal clear and free of bacteria. You can relax knowing that your water is always perfectly safe for soaking.