Automotive coolant refractometer measures the freezing point of coolants plus battery charge condition. Requires only a few drops of solution to use. Measures the freezing point of coolants Measures battery charge condition Provides accurate and repeatable measurements of % ethylene glycol and propylene glycol and °F on easy to read scale Propylene range: -60°F (63%) to 32°F (12°) Glycol range: -60°F (59°) to 25°F (16%) Specific gravity of battery acid: 1.15 to 1.30 Automatic temperature compensation Requires only 2 to 3 drops of solution Prism and lens with a simple focus adjustment provides repeatable results Includes calibration screwdriver, calibration solution and case Model RF40 1-year limited warranty