H-B DURAC 0/20 Percent Alcohol Proof &ndash; Ethyl Alcohol Hydrometer (B61807-4200) Made according to the Bureau of Internal Revenue, U.S. Treasury Department, the tolerances listed for these hydrometers are those outlined in Circular 555 of the National Bureau of Standards, Testing of Hydrometers; Internal Revenue Code F Used to determine proof of ethyl alcohol spirits Length: 300mm (12); Range: 0/20%; Divisions: 0.2%; Accuracy: 0.2% Individually serialized; lead free ballast and glass; Temperature of standardization: 60F (15C) Packaged with a multi-language (English, French, German, Italian, Portuguese, and Spanish) Statement of Accuracy indicating accuracy traceable to NIST