Analog Refractometer Hand-Held Range 1.100 to 1.43 Automatic Temperature Compensation Yes Accuracy +/-0.5 Percent Resolution 0.01 Function Determines The Freeze Point of Antifreeze and Battery Acid By Measuring The Degree of Which Light Bends As It Passes Through The Sample The Refractive Index Measured is Then Converted to Percentage of Water to Propylene or Ethylene for Easy Reading Freezing Point -76 Degrees to 32 Degrees F