Hanna HI-772-11 Calibration Checking Set For The HI-772 Marine Alkalinity Checker The HI-772-11 is a calibration checking set for use with the HI-772 Marine Alkalinity checker. The Marine Alkalinity (dKH) Checker HC Calibration Check Set – HI-772-11 provides a simple solution to validating the Marine Alkalinity Checker HC – HI-772 that has a range of 0.0 to 20.0 dKH.