Durac Safety combined form hydrometers measure temperature and relative density of liquids compared to water in food & beverage, chemical, pharmacology, transportation and refrigeration industries. They have lead free ballast and glass construction with mercury-free blue spirit organic liquid for accurate measurements. These hydrometers measure temperature in the range of 0 to 150 degrees F or from 0 to 50 degrees C and feature 3 different types of scales for measuring relative densities. A specific gravity scale measures the relative density of liquids compared to the density of water, whereas an API hydrometer measures the specific gravity of petroleum products and a sugar or Brix hydrometer determine sucrose content in a liquid solution.