Certified Reference Material (CRM) solutions meets all test requirements for federal, state and local agencies 100% compatible with all makes of pH instruments and electrodes Long term buffer stability and buffer resistance to temperature changes during pH meter calibration Manufactured to IUPAC (International Union of Pure and Applied Chemistry) formulation Triple-layered proprietary packaging (aluminum, foil, PET and low-density polyethylene bag) prevents contamination by permeable gases Supplied withindividual temperature chart, traceability information and Traceable™ Certificate