Professional design: developed for testing the concentration of salt water and saline solution, it is very suitable for aquariums, ocean monitoring, aquaculture fish, shrimp, crab, coral, etc. as well as for quality control in research and clinical laboratories.Wide measuring range: salt content 0-100 (0-10% salt content), density 1000-1070 SG, accuracy: salt content +/- 1%, density +/- 0.001 SG, accuracy: 0.2%. Note: If you need to measure the concentration of salt water above 10%, please buy a salinity refractometer from 0-28%.High quality material: our chrome-plated brass housing is resistant to chemical corrosion and wear resistance. The life of the refractometer is many times longer than other aluminium housings, which are safe and durable.Precision measurement: the dividing line is clear (blue and white), easy to read (visible under daylight) and the eyepieces can be adjusted to clarity.Easy to use: add 2.3 drops of the sample to the main prism, close the panel and check the salt content through the observation window. The measurement results are clear at a glance.dual scale salt refractometer is used to measure, monitor and control salt and brine concentration, especially for aquarium and marine applications.