The 4×25 pack of reagents is for use with the HI-701 Free Chlorine Pocket Checker.

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 HI-701-25 reagent, the reaction will take place and the HI-701 will determine the concentration from the colour 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.