Antifreeze tester refractometer RHA-503ATC models are equipped with C unit system. 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. There\'s also an additional scale for measuring the freezing point of windshield cleaning fluid. It\'s FULLY EQUIPPED with ATC that automatically adjust itself to correct temperature discrepancies during use. Specifications: Measuring Range: Ethylene Glycol: -50C-0C Propylene Glycol: -50C-0C Cleaning Fluids: -40C-0C Battery Fluids: 1.100-1.400sg Resolution Factor: Ethylene Glycol: 5C Propylene Glycol: 5C Cleaning Fluids: 5C Battery Fluids: 0.01sg (ATC) Temperature Compensation Range: 10C-30C Approved by strict quality and safety standards Durable and built to last long Heavy-duty and lightweight with its aluminum construction Easy to focus and calibrate Accurate testing results guaranteed Made with the highest and finest quality of aluminum & rubber that makes it lightweight Cushioned with soft & comfortable non-slip rubber Extremely easy-to-use and calibrate Packing list: 1*Antifreeze tester refractometer