A dual scale refractometer quickly measures how much sugar is in a solution on a both a brix and specific gravity scale. The more sugar in solution, the higher the reading. Just put a few drops of wort or juice on the lens and close the cover. Then look through the eyepiece to read the sugar content in both brix and specific gravity (brix 0-32, specific gravity 1.000 to 1.130).
A refractometer is not a replacement for a hydrometer, as it cannot easily be used to check the brix or specific gravity of sugar solutions that contain alcohol. To do this with a refractometer, you can use brewing software like BeerSmith*. However, it is ideal for quickly checking initial sugar content, whether in the field when checking the ripeness of grapes, or when mashing to immediately see the specific gravity of the runoff.
Not all refractometers are the same. The picture at right shows a comparision view at the same camera exposure of our William's Refractometer on the right and a generic refractometer on the left with the same light source. Note the brighter and larger display made possible by the higher quality optics in the William's Refractometer.
Ours also features automatic temperature compensation, a vision adjustable eyepiece with removeable rubber eye cup, leatherette holster case (for carrying while hiking through the vineyard), cleaning cloth. eyedropper, padded case, calibration screwdriver (calibrate to zero brix/specific gravity by using tap water) and instructions.
This shows the case and accessories.