The Milwaukee MA871-BOX is a digital refractometer (optical instrument) that employs the measurement of refractive index to determine the % Brix of sugar in aqueous solutions, and includes a protective hardshell case. The method is both simple and quick. Samples are measured after a simple user calibration with deionized or distilled water. Within seconds the instruments measure the refractive index of the sample and convert it to % Brix or % by weight concentration units. The MA871 eliminates the uncertainty associated with mechanical refractometers and is easily portable for measurements in the field. The measurement technique and temperature compensation employ methodology recommended in the ICUMSA Methods Book (Internationally recognized body for Sugar Analysis). Temperature (in °C or °F) is displayed simultaneously with the measurement on the large dual level display along with icons for Low Power and other helpful message codes.