A refractometer is a widely used in pharmaceutic factory food insdustry or research laboratory for the measurement of an index of refraction, particularly for determining the strengthof lenses for spectacles. Juices, Beverages, Honey, Salt water, Brine, Cleaning fluid, battery fluid, Antifreeze and Industrial fluids etc. And they can also test for the proportion of the water-soluble solution Rok International Industry Co. Limited provide all kinds of professional refractometer,There are four main types of refractometers: traditional handheld refractometers, digital handheld refractometers, laboratory or Abbe refractometers, and inline process refractometers. There is also the Rayleigh Refractometer used (typically) for measuring the refractive indices of gases.