Measurement Range and Minimum Scale: Sugar: 0–40%, Minimum Scale: 0.2 Alcohol Content: 0–25% Automatic Temperature Compensation function to minimize temperature-induced data deviation for improved accuracy. Enhanced eyepiece with heavy crown optical glass lens (not standard glass) for superior 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 distilled water (calibration standard). Ensure both instrument and sample are at the same temperature. Lift the cover, place 1–2 drops of distilled water onto the prism surface, gently close the cover to form a distinct light/dark boundary line. Adjust the calibration screw so this boundary aligns precisely with the 0% reference line in the eyepiece view. Note: This optical instrument is factory-calibrated and ready for immediate use. 3) Lift the cover, wipe the prism surface gently with a soft cloth. Place 1–2 drops of the sample solution onto the prism, close the cover gently, and read the corresponding scale value where the light/dark boundary intersects — this indicates the solution’s concentration and density. 4) After measurement, clean the prism surface and cover plate with a damp, soft cloth. Dry thoroughly and store the device properly. Calibration: Zero-point calibration is required before each use. Apply a few drops of distilled water to the prism, adjust the zero-setting screw until the light/dark boundary 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 vibrations. 2. Never immerse the instrument in water for cleaning. Use only a clean, soft cloth to 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 construction, shock resistance, ease of operation and portability, clear optical view, 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 fields. Salt-series refractometers are used in marine aquaculture, aquarium maintenance, 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 fluids, refrigerants, cleaning solutions, machine tool lubricants, and cutting fluids.