Hand Held Brix Refractometer 0-32% Brix Saccharimeter Sugar Tester ATC Refratometro For Fruit Vegetables Juice Type : Prism refractometer Equipped with scale measurement which provides direct reading. Extremely easy-to-use and calibrat. Adjustable manual focusing. Uses ambient light only which means battery or power source is not required. Measuring range: 0 - 32% Brix. Reference Temperature: 20degC. ATC(Automatic Temperature Compensation) Compensation Range: 10degC~30degC (50degF~86degF). Manual calibration with mini-screw driver provided. 1. Align the Cover Plate with light, adjust the Focus Adjustment until you see the scale clearly. 2. Calibration: Accurate Measurement depends on careful calibration. Please make sure the ambient temperature is about 68 degF, distilled water can be used to calibrate. A. Open the Cover plate. place 2-3 drops of the distilled water on the prism, then close the cover plate and make sure the water spread aro the prism without any air bubbles or dry spots. wait for about 30 seconds to let the reading to stabilize. Look into eyepiece and turn the calibration screw with the screw driver until the reading is "0" 3. Clean the prism with soft cloth, then place 2-3 drops of the liquid sample to be tested on the prism. then close the cover plate and make sure the water spread aro the prism without any air bubbles or dry spots. wait for about 30 seconds to let the reading to stabilize. Align the prism aembly with the light source. look into eyepiece and you can get the reading. 4. Please keep the refractometer dry and clean in the box, which can make sure the reading accuracy and durable.