The HI 718-25 is a set of 25 iodine reagent packets for use with the HI 718 iodine meter.
A reaction between the reagent and iodine in a sample causes a pink tint to appear, which is measured by the meter. The meter uses an Adaptation of the Standard Methods for the Examination of Water and Wastewater, 18th edition, DPD method to determine the amount of iodine present.