Review on Enhancing Precision with Apera Instruments' Waterproof Pocket Accuracy by Chris Russell

Includes quality certificate card tested at 84 mS/cm, 1413 mS/cm and 12.88 mS/cm, with article number, serial number and country of origin. The instructions are easy to follow (although the font is too small, they include a laminated instruction card and you can download the instructions in PDF format from the factory). The kit comes with 2 vials of calibration solution that I use every time I measure my APEC reverse osmosis system (probably overkill). The instrument was calibrated at the factory and according to the instructions, one solution (1413 mS/cm) is sufficient for calibration. An important tip for extending the life of the calibration solution is to avoid contamination. Simply rinse and dry the probe tip before and after each measurement/calibration. The manufacturer recommends changing the calibration solution after 5-10 calibrations to maintain its accuracy.