The PIOX R is a refractometer sensor made by Flexim company. The sensor consists of a transmitted light measurement and it can reach a precision and zero point stable. A Pt1000 probe cares for the temperature compensation in accordance of the customer-specific fluid data that can be implemented with a RMKoeff software tool. The unit determines the customer specific output number of the mass concentration of a solution. It also provides useful tools to detect errors. The refractometer is method of choice to determine the concentration, density and purity of many liquids. The device operates in accordance to the transmitted light principle. It determines the refractive index of the liquid as the basis of the measurement of the angle. The device can be used in the most diverse applications.