The HI762-25 are high-quality reagents that are pre-measured, allowing for users to achieve fast and accurate measurements with their Free Chlorine Ultra Low Range Checker^® HC. These reagents follow the DPD Method in which the reaction between chlorine and reagent causes a pink tint in the sample. By simply adding the packet of HI762-25 reagent to the sample, the reaction will take place and the HI762 will determine the concentration from the color that is produced. The results will be displayed in ppb of free chlorine.