Salinity Refractometer is designed for testing the concentration of salt water and brine and used for quality control in research and clinical laboratories and marine industry. Its scale provides a direct reading of the specific gravity and concentration (part per Thousand) of salt in water. One scale checks the NaCl levels with the range of 0-100 ppt (with 1 ppt scale divisions) and the other scale gauges Specific Gravity with a range of 1.000 to 1.070 (±0.001 accuracy). Both enables the direct determination of salinity in water that contains dissolved salt and little or no other dissolved solids. It is suitable for a marine saltwater tank.