USE: This is an optical refractometer designed to measure alcohol content by mass. It is not suitable for measurements of alcohol content in liquor, beer or wine! If you know the weight of the distillate in kilograms and use the refractometer to measure alcohol content by volume, you can calculate the mass fraction of pure alcohol in kilograms by multiplying the two values and dividing the result by 100. Measuring range: Alcohol: 0-80% v/v, Resolution: Alcohol: 1% v/v Sharp precision measurement division line (blue-white), easy to read (daylight visible), adjustable eyepiece for focus adjustment < p>Calibration: zero calibration with distilled water at 20C, automatic temperature compensation between 10C and 30C (ATC). Product description: < p>This refractometer is used to determine the alcohol content in liquids and is used for distillation processes of all kinds, for example in distilleries. It is an optical refractometer designed to measure the percentage by weight of alcohol. It is not suitable for measuring the alcohol content of liquor, beer or wine! With the refractometer you can : Accurate test results - Uses ambient light, no batteries or power source required. -For area application without having to recalibrate for changes in ambient operating temperature. -Measuring distilled drinks, e.g. whiskey, brandy, fruit brandy, slivovitz, vodka, gin, tequila, etc. Measuring range: 0-80% v/v alcohol Resolution: 1% v/v alcohol