Fuloon Professional Automatic Temperature Compensation Sea Water Salinity Refractometer for Aquarium, Hydrometer, 0-100ppt & 1.000-1.070 Salinity Specific Gravity Product structure: deviation prism + cover + calibration bolt + optical system pipeline +eyepiece (diopter adjustment ring) Salinity meter designed to measure salt solution, the concentration of salty food, seawater and saltwater. Features with two scale line to directly read Measuring range: salinity: 0-100 , Specific Gravity : 1.000 to 1.070 Minimum scale: salinity: 1 , Specific Gravity : 0.001 Resolution: salinity: 1, Specific Gravity : 0.001 mm