Glycol antifreeze freezing point: -50 to 0 °C, with a division value of 1 °C. Propylene glycol antifreeze freezing point: -50 to 0 °C, with a division value of 1 °C. Electrolyte specific gravity: 1.10 to 1.40, with an index value of 0.01. (1.15 to 1.20 requires charging; 1.20 to 1.25 indicates sufficient charge; 1.25 to 1.30 indicates full charge). Windshield cleaning fluid freezing point: -40 to 0 °C, with a division value of 5 °C. Includes: 1 x Refractometer 1 x Screwdriver 1 x User manual 1 x Cleaning cloth Use: This refractometer allows you to determine the concentration of ethylene glycol and propylene glycol in antifreeze used in vehicles, solar systems, heat pumps, heating systems, and other machinery. It can also measure the freezing point of windshield washer fluid and urea concentration, as well as battery electrolyte specific gravity. Measuring Range: Ethylene glycol (ethanediol): -50 °C to 0 °C Propylene glycol (propanediol): -50 °C to 0 °C Windshield washer fluid (ethanol + water): -40 °C to 0 °C Propylene glycol + water (SRF1): -40 °C to 0 °C Urea concentration: 30% to 35% Battery acid specific gravity: 1.10 to 1.40 kg/L Temperature Compensation: Built-in automatic temperature compensation ensures accurate and reliable measurements under varying conditions. Precision Measurement: Equipped with an adjustable eyepiece and optical system offering 4x to 8x magnification with stepless manual focus. Designed to accommodate all users' visual preferences. High Quality: Durable chrome-plated brass construction provides excellent resistance to chemical corrosion and wear, significantly extending the service life compared to aluminum-bodied models.