A refract meter 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 refract meter is a precise optical instrument. Its characteristics are small, light, take only a few drops of solution to use and is very user friendly. Refract meters are used throughout the food, agriculture, chemical and manufacturing industries. General"s REF312ATC Protein and Urine Refract meter with Automatic Temperature Compensation has a metal body with cushioned eyepiece, a rubber hand grip and a calibration screen. Includes a calibration screwdriver, a plastic pipette and a carrying case.