The HI721-25 are the replacement reagents for the HI721 Iron Checker® HC. These high-quality reagents are manufactured in our state-of-the-art facility and are clearly marked with the lot number and expiration date on each packet for traceability. The HI721-25 are high-quality reagents that are pre-measured, allowing for users to achieve fast and accurate measurements with their Iron Checker HC. These reagents follow the Phenanthroline Method in which the reaction between iron and reagent causes an orange tint in the sample. By simply adding the packet of HI721-25 reagent to the sample, the reaction will take place and the HI721 will determine the concentration from the color that is produced. The results will be displayed in ppm (mg/L) of iron. These reagents are designed to be used with samples that have an expected range of 0.00 to 5.00 ppm (mg/L) iron.