The HI701-25 are high-quality reagents that are pre-measured, allowing for users to achieve fast and accurate measurements with their Free Chlorine 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 HI701-25 reagent to the sample, the reaction will take place and the HI701 will determine the concentration from the color that is produced. The results will be displayed in ppm (mg/L) of free chlorine. These reagents are designed to be used with samples that have an expected range of 0.00 to 2.50 ppm free chlorine.