These tablets are manufactured with the most concentrated form of dry chlorine available today. They are consistent in size and slow dissolving in nature to allow you to reliably dose your pool just once a week. These tablets contain cyanuric acid - a stabilizer that prevents ultra violet light from removing available chlorine from your pool. These tablets allow you to easily maintain proper chlorine residuals and help you to effortlessly produce beautiful, clean sparkling water. How to use: Apply chlorinating tablets to your feeder (or chlorinating device ).1 tablet treats 10000 gallons of water for up to a week. NOTE: These tablets are individually wrapped. Some of the tabs may be cracked or broken within their individual packaging due to shipping. This breakage is normal and does not reduce the effectiveness of the chlorine tabs. The C3 3 inch stabilized chlorinating tablets are slowing dissolving and will keep your pool free of bacteria and algae. Can be used with a automatic chlorine feeder, a floating dispenser or placed in a skimmer basket.