Measurement Range and Minimum Scale: Sugar: 0–40%, Minimum Scale: 0.2 Alcohol Content: 0–25% Automatic Temperature Compensation function to minimize data deviation caused by temperature fluctuations, ensuring higher measurement accuracy. Improved eyepiece design with heavy crown optical glass lens (not standard glass) for enhanced clarity and reduced observer eye fatigue. Usage Instructions: 1) Point the refracting prism toward a light source. Adjust the eyepiece focusing ring until the reference line appears sharp and clear. 2) Calibration: Before measurement, prepare calibration liquid (distilled water). Ensure both instrument and sample are at the same temperature. Lift the cover plate, place 1–2 drops of distilled water onto the refracting prism, gently close the cover to form a distinct light/dark boundary line. Turn the calibration screw until this boundary aligns precisely with the 0% reference line in the eyepiece field of view. Note: This optical instrument is factory-calibrated and ready for immediate use. 3) Lift the cover plate, wipe the prism surface with a soft cloth, apply 1–2 drops of the test solution onto the refracting prism, gently close the cover, and read the corresponding scale value at the light/dark boundary — this indicates the concentration and density of the tested liquid. 4) After measurement, clean the prism surface and cover plate with a damp soft cloth. Dry thoroughly before storing the instrument properly. Calibration: Zero-point calibration is required before each measurement. Place a few drops of distilled water on the detection prism, adjust the zero-setting screw until the boundary line aligns with the 0% mark on the scale. Wipe the prism clean and proceed with testing. Some models may require a standard solution instead of distilled water for calibration. Precautions: This is a precision optical instrument. Observe the following during use and maintenance: 1. Handle with care. Follow instructions strictly. Do not loosen any connecting parts arbitrarily. Avoid dropping, impact, or strong vibration. 2. Never immerse the instrument in water for cleaning. Use only a clean, soft cloth to gently wipe optical surfaces. Avoid scratches or damage. 3. Store in a dry, non-corrosive environment. 4. Prevent loss of small detachable parts. Applications: Refractometers offer advantages including simple robust construction, shock resistance, ease of operation and portability, clear optics, and cost-effectiveness. Sugar-series refractometers are used in food preservation, fruit juice manufacturing, brewing and fermentation, beverage production, fruit processing, honey harvesting, and related industries. Salt-series refractometers are used in marine aquaculture, aquarium management, and physiological saline preparation. Medical-series refractometers are used for serum protein and urine specific gravity testing. Industrial-series refractometers are used for testing automotive battery electrolytes, refrigerants, cleaning solutions, machine tool lubricants, and cutting fluids.