Hydrometers are for reading density of a mash, and are used to confirm completion of fermentation, or to calculate the alcohol content from fermentation by using readings at the start and end of fermentation. Hydrometers will not work in a distilled spirit. 

Has both Specific Gravity Scale and Potential Alcohol scale. 0.980 to 1.170 Specific Gravity reading - 30cm (12'') long laboratory grade Hydrometer.