HI-762-11 is a high-quality set of calibration standards that allows users to validate the Free Chlorine Ultra Low Range Checker®HC – HI-762. The HI-762-11 includes one sealed cuvette for zero ppb free chlorine and one cuvette that is tinted to an equivalent of +/- 20 ppb +/-4% of reading free chlorine sample @ 25°C. The calibration check set is produced using reagent grade chemicals in a temperature controlled environment.