The "G&W Bottle Hydrometer" measures liquid density or specific gravity (S.G.) to monitor fermentation and sugar levels.
Length: 26 cm (10.2")
Range: 0.980-1.020° (.001 divisions)

Calibrated at 60°F (15.5°C)

 

• This hydrometer has been calibrated in accordance with the A.S.T.M. standard E 126 and N.I.S.T. circular No. 555. The instrument is traceable to N.I.S.T. having been calibrated against an instrument which has been certified by the National Institute of Standards and Technology.

To determining the alcohol content use the alcohol scale on the hydrometer. Take one reading before fermentation. Take the final reading after fermentation is complete. E.g.

The difference between the first and last reading gives you the percentage of alcohol in your wine, e.g. First reading is 11% (S.G – 1.085). Final reading is minus 1% (S.G – 0.992). The difference between these readings is 12%, which means your wine is 12% alcohol by volume.