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 , rotate lightly, not easy to off. Clear , fast detection, accurate measurement, easy to use.suitable for canned food, manufacturing, brewing and fermentation, beverage, fruit, honey 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 (ATC): 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 picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.