Hanna Copper Low Range Reagent Set for HI 747 Checker HC are super accurate replacement reagents for the Hanna HI 747 Copper Low-Range Checker HC. These pre-measured reagents are prepared with high purity chemicals and can be used with samples in the 0-999 ppb copper range. The reagents adhere to the Bicinchoninate Method in which the reaction between copper and the reagent causes an easy to see purple tint in the sample. Comes with 25 tests.