The General Tools REF112ATC refractometer is ideal for measuring the salinity, specific gravity (SG), refractive index (RI) or viscosity of industrial fluids. A refractometer is an instrument that measures the concentration of an aqueous solution by measuring its refractive index. All water-based solutions can make light bend. The bending of light increases at a rate proportional to the increasing solution concentration. The hand held refractometer is a precise optical instrument. Its characteristics are small, light, take only a few drops of solution to use and is very user friendly. Refractometers are used throughout the food, agriculture, chemical and manufacturing industries. Our analog and digital refractometers are among the finest optical instruments in the world. We offer a full line of refractometers that are suitable for all applications: Brix, Alcohol, Propylene Glycol, Protein in serum, Salinity, Baume, Specific Gravity, Industrial Fluids, Refractive Index (nD), along with many other scales which provide the user with limitless flexibility.