A refractometer can be used to judge when fruits and vegetables are at their peak for harvesting, or it can be used to select plants based on sugar content for propagation or harvesting programs. Similarly, it can be used to judge potential alcohol content from juice you intend to ferment (but it does not directly test the alcohol content of the finished product).
The tester is simple to use; just add a drop of juice to the end and look through it against a bright light. A line will show on the internal scale to let you know the exact sugar content and potential alcohol content. If you are making alcohol and the sugar level is too low, more sugar can be added.
Measures from 0 to 40% sugar (to an accuracy of 1/5 of 1%) and estimates 0 to 25% potential alcohol. An unusual and very useful tool.
6 1/2" overall. Complete with storage case, juice dropper and instructions.