The refractometer is used for measuring Specific Gravity of Wort and density of sugar related liquids such as fruit juice, soft-drinks, wine and wort. In Beer or Wine use the refractometer readings to get wort sugars and help determine finished alcohol readings (for alcohol reading, best used in conjunction with a hydrometer). Refractometers are a must have for All Grain Brewing, especially during the mash and lauter stages. Works great with a Refractometer Lens Light.
Note that a refractometer gives an inaccurate reading on already fermenting or fermented beer. You can use a refractometer correction caclulator to get a more accurate reading, but the use of a hydrometer in a throughly degassed beer will give more accurate results.
Works like a charmThis does exactly what you would expect. It is much easier to use than a hydrometer. I've checked the measurements many times against a hydrometer, and they always match.
This can only be used before fermentation--alcohol affects measurements.