The Triplett RFT55 (°F) Portable Portable Battery Coolant/Glycol Refractometer measures the freezing point of Propylene/Ethylene Glycol and Battery Acid specific gravity. It requires only 2 to 3 drops of solution for accurate measurement. ATC automatically compensates for ambient temperature changes from 50° to 86°F (10° to 30°C). Easy calibration with distilled water. Includes screwdriver, cleaning cloth, pipette, and case.