1.Measure salt water or water salinity, ideal for Seawater Aquarium Tank,Marine market and marine monitoring 2.Salinity measurement range: 0-100 PPT with 1ppt resolution; Salinity Proportion(D 20/20)(D 20/20): 1,000~1,070 with 0.001 resolution 3.Easy to use, place 2-3 drops of sample on main prism, close plate and look through the eyepiece for brix reading 4.Versatile refractometer with automatic temperature compensation (10°C~30°C), calibration screw (Calibrate at “0”) ensures accurate measurement and focus adjustment ensures clear reading 5.Portable Refractometer, sturdy design, compact in size and lightweight, lined with plastic case, convenient to keep and carry