This triple scale hydrometer is a measuring instrument used in brewing and winemaking to determine the sugar content, or specific gravity, of liquids such as beer wort or grape juice. The hydrometer has three scales, each measuring different aspects of the liquid. The first scale measures the specific gravity, which is a measure of the density of the liquid compared to water. The second scale measures the potential alcohol content based on the difference between the original and final specific gravities. The third scale measures the Brix, which measures the sugar content of the liquid.
The hydrometer is used by floating it in the liquid and reading the specific gravity, potential alcohol, or Brix from the scale.