1. Ethylene glycol: -50°C - 0°C (concentration 0 - 70%) Propylene glycol: -50°C - 0°C (concentration 0 - 70%) Resolution coefficient: 5°C, 5% (automatic temperature compensation) Temperature compensation range: 10°C - 30°C 2. Field of view: Middle scale: (Ethylene glycol) Freezing point of ethylene glycol - type antifreeze. (Propylene glycol) Freezing point of propylene glycol - type antifreeze. Left scale: (Battery fluid) Specific gravity of battery fluid. 1.15 - 1.20 Needs charging 1.20 - 1.25 Sufficient power 1.25 - 1.30 Ample power Right scale: Freezing point of glass cleaning fluid 3. Working principle: This instrument can measure the freezing points of antifreeze and glass cleaner, and the specific gravity of lead - acid battery electrolyte. It is equipped with a temperature compensation device to ensure simple and convenient measurement and accurate measurement at an ambient temperature of 10°C - 30°C. Its basic principle is to measure the refractive index of the solution using the total reflection critical angle method, and then calibrate the concentration and performance of the measured liquid. Due to its reliable principle and accurate measurement, it can meet practical needs. It also has the characteristics of small size, light weight, beautiful appearance, and convenient use, so it is widely used in the automotive industry. 4. Usage precautions: (1) Do not place the instrument in an environment with a relative humidity exceeding 85% for a long time to avoid affecting the optical system. (2) Do not let liquids and water enter the adjustment knob and the eyepiece to avoid damaging the internal components. (3) Do not subject it to severe vibration and collision to avoid damaging the instrument's accuracy. (4) After use, immediately wipe the prism and the refraction plate clean with a clean cloth. 5. List of accessories: (1) 1 refractometer (2) 1 pipette (3) 1 instruction manual (4) 1 mini - screwdriver (5) 1 cleaning cloth