Refractometer technology is based on the principle of refractive of different liquid concentrations, which is an optical instrument with high accuracy and portability. calibration screw: drop distilled water on the , twist the adjustment screw, so that the dividing is adjusted to the scale 0%. Adjustable eyepiece: When the scale in the territory is not clear, you can gently rotate the eyepiece to adjust it. anti-corrosion and anti-rust, as new, beautiful . Anti-slip rubber cover feel soft, rotate lightly, not easy to slip off. Clear reading, fast detection, measurement, easy to use. suitable for canned food, manufacturing, and fermentation, beverage, fruit, harvesting and other fields. Brix test range 0-90%, measurement accuracy: 0.1%. With temperature compensation function, to overcome the deviation of data caused by temperature changes, making the data more . Item Type: Refractometer Model: RHB-90ATC Sugar Test Range 0-90% Measurement Accuracy: 0.1% Automatic Temperature Compensation (): 10~30 (50~86) Package List: 1 x Refractometer 1 x Dropper 1 x Screwdriver 1 x Cloth(random colors, 't accept the specified color) Colour:As Shown Material:Metal Package Contents: 1 set x brix tester Only the above package content, other are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.