Hydrometers are an essential tool that allow homebrewers to measure the amount of sugar content in their wort. Beer hydrometers essentially just gauge how much sugar there is in a liquid. Taking this measurement both at the beginning and the end of fermentation enables one to calculate the amount of alcohol in the finished beer and to estimate how well the yeast has performed. The Triple Scale Hydrometer, which tests starting and finishing beer gravity, or sugar content, in beer or wine fermentations, has three scales: specific gravity, potential alcohol and brix. The Proof and Tralle Hydrometer is an alcohol hydrometer to measure the alcohol content in a liquid. Distilleries use Proof and Tralle hydrometers to check the proof or alcohol content of their products.