HI774-11 is a high-quality set of calibration standards that allows users to validate the Phosphate Ultra Low Range Checker® HC - HI774. The HI774-11 includes one sealed cuvette for zero ppm phosphate and one cuvette that is tinted to an equivalent 100 +/- 10 ppm phosphate sample @ 25°C. The calibration check set is produced in our state-of-the-art manufacturing facility using reagent grade chemicals in a temperature controlled environment.