For liquids heavier than water, each hydrometer is calibrated in a triple accredited ISO/IEC 17025:2005, A2LA accredited laboratory against equipment whose calibration is traceable to NIST. Individually packaged with a multi-language Statement of accuracy indicating accuracy traceable to NIST. Whats included: choose from our comprehensive line of hydrometers and other hydrometers products. Nist traceable temperature of standardization 60°f/60°f metal ballast individually serialized.