Use NIST-traceable reference materials for the highest accuracy available. Traceable™ Conductivity Calibration Standards Certified Reference Material (CRM) offer easy calibration with included instructions and temperature chart. Traceable Conductivity Calibration Standards Certified Reference Materials (CRM) offer easy calibration with included instructions and temperature chart. For the highest accuracy available, use NIST-traceable reference materials. Each bottle includes a NIST-traceable calibration report supplied by the manufacturer and information from batch testing. Also includes step-by step calibration instructions and temperature compensation chart. Accuracy at 25°C is (±0.25 microsiemens for 1, 5, 10 microsiemen solution or ±0.25% for other solutions) or the uncertainty shown on the certificate, whichever is greater.