Apera Instruments AI1121 pH 1. 68 Calibration Buffer Solution is color-coded and standardized against NIST certified pH references within 0. 01 pH at 25°C (77°F). It's ideal for the calibration of pH meters/testers that can automatically recognize pH 1. 68 standard e. g. Apera PH60, PH700, PH800, PC400S. Since pH level is affected by temperature, a temperature/pH reference chart is provided on the bottle label for reference. All the solutions are double-sealed, not subject to the DOT shipping restrictions, and have a 2-year shelf life. The expiration date is printed on the bottle. MSDS documents are downloadable. Certificate of analysis can be achieved by request. Note: Store at room temperature and away from direct sunlight. Keep the bottle tightly closed when not in use. Keep out of reach of children.