The models have only one unit system: °C.  With the indication of the percentage we may know the freezing point of either ethylene glycol or propylene glycol based cooling systems. And  they can also be used to test the concentration of ethylene glycol or propylene glycol in antifreeze liquids. The RHA-200ATC has Automatic Temperature Compensation System. 

该型号折射仪被用于测量以乙二醇和丙二醇两者为基的汽车冷却系统水溶液的冰点温度值和浓度百分比，它还可以检查蓄电池内电解液的比重及使用状态。冷却系统水溶液冰点为摄氏度标定。