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 zero adjustment screw, so that the dividing line 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, bright as new, beautiful atmosphere. Anti- rubber cover feel soft, rotate lightly, not easy to off. Clear reading, fast detection, accurate 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 accurate.Item Type: RefractometerModel: RHB-90ATCSugar Test Range 0-90%Measurement Accuracy: 0.1%Automatic Temperature Compensation (): 10~30 (50~86)Package List:1 x Refractometer1 x Dropper1 x Screwdriver1 x Cloth(random colors, 't accept the specified color) Colour:As ShownMaterial:MetalPackage Contents:1 set x brix testerOnly the above package content, other products 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.