H-B DURAC 30/50 Percent Alcohol Proof Hydrometer (B61807-0100) DURAC alcohol proof precision hydrometer is for waste liquors Range: 30 to 50%; Divisions: 0.002%; Accuracy: +/-0.4% proof.; Temperature of Standardization 60F/60F Length: 250mm (9.8in) Individually serialized and features a metal ballast Tested and calibrated in our exclusive triple accredited/registered ISO/IEC 17025:2005, A2LA accredited laboratory against equipment whose calibration is traceable to NIST and DKD/PTB