The No. 1 DPD reagent tablets are a high-quality and reliable method for determining chlorine levels in water. With this 250-count pack of DPD reagent tablets, you can perform a variety of tests to ensure your pool or spa is clean and safe for swimming. The DPD reagent tablets are easy to use: simply add one tablet to a sample of pool water and observe the color change. Based on the color change, you can determine the chlorine level and take appropriate action to disinfect and maintain the water. The DPD reagent tablets are of high quality and provide accurate results, so you can be sure your pool water is clean and healthy. With this convenient 250-count pack, you'll have enough reagent tablets to last a long time and can perform regular tests to monitor water quality and ensure your pool or spa is always ready for a refreshing dip.