Also known as a proof meter or alcohol hydrometer, this measures % abv for distilled spirits. It has % alcohol by volume and % proof measurements. It does not measure % abv for beer, wine, or other beverages – this is not a hydrometer and does not measure gravity! This works because it is calibrated for the difference in weight between water and alcohol, but if sugars, proteins, etc are in the solution, it will not be accurate. Hence why it only works for distilled liquids.
