This optical refractometer is designed for measuring coolant and antifreeze based on ethylene glycol or propylene glycol ,battery fluid condition and screenwash antifreeze (windshield washer fluid) based on ethanol as well as on isopropyl alcohol. Please refer to the above picture of display scale, from left to right, the first scale is for measuring the Specific Gravity of Battery Acid, the second one is for measuring the freezing point of antifreeze system based on propylene glycol or ethylene glycol, the third one is for measuring the freezing point of the windscreen cleaning liquids.