The Marine Calcium Checker® HC Calibration Check Set - HI758-11 provides a simple solution to validating the Marine Calcium Checker® HC - HI758 that has a range of 200 to 600 ppm calcium. This high-quality set of standards is manufactured in our state-of-the-art facility and comes supplied with a Certificate of Analysis. The Certificate of Analysis provides the lot number, reference values and expiration date for traceability when certifying the Checker®HC. - Supplied with Certificate of Analysis - Standard value of 400 +/- 20 ppm calcium @ 25°C - Reusable with long shelf life stability