Fangrui Product Details 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 - Brix. Reference Temperature: 20degc.atc(automatic Temperature Compensation) Compensation Range: 10c~30c (50f~86f).manual Calibration With Mini-screw Driver Provided. Type : Prism Refractometer. Wort S.g.1.000-1 .120sg. One Scale: Brix Scale: 0~brix;. Reference Temperature: 20c How To Operate: 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 Aross The Prism Without Any Air Bubbles Or Dry Spots. Wait For About 30 Seconds T