Saber LED Refractometer - Water Resistant - Three Scale (incl Case, Charging Cable)Getting fast, accurate, and reliable readings during all grain brewing is essential to getting the best possible efficiencies. Refractometers help you achieve this and can speed up your brew day significantly. Now in a water resistant design that is rechargeable! This high quality refractometer is extremely accurate and easy to use and calibrate. Calibration is simply done with a few drops of distilled water and the use of a flat head screwdriver.