Hanna Conductivity Calibration Solution 12880 uS/cm H7030L is a premium quality 12,880 µS/cm conductivity solution standardized with a conductivity meter that has been calibrated with potassium chloride NIST 2202 SRM (Standard Reference Material) in deionized water for analytical use by ISO 3696/BS3978. Additional equipment used in the preparation of the solutions includes certified weight-checked balances, Class A glassware, and certified thermometers.