Usage: With this refractometer clips the ethylene glycol and propylene glycol concentration of frost protection to your car, their solar installation, heat pumps, freezing point disc, heating installation or other machines or water installations to determine. MEASUREMENT RANGE: Ethanediol (ethylene glycol): 0 to -50C; Propanediol (propylene glycol): 0 to -50C; Windscreen cleaning fluid - ethanol + water: 0C to -40C, propylene glycol + water (SRF1): 0C to -40C. AdBlue: urea concentration 30% - 35% Acid battery from 1.10 to 1.40 kg / L. Precision measurement: Adapt the optical system of the eyepiece group: 4-8 times amplification system, stepless manual focus. Can fit all eyes. To cover nearsightedness and farsightedness, you should not observe the measured data with glasses. Calibration: zero calibration with distilled water at 20C, automatic temperature compensation. Please note that due to manual measurements and display differences, there may be slight differences between individual products and photos.