The Extech RF20 measures the concentration of dissolved salt in fluids. It has a compact size and is easy to operate. Automatic Temperature Compensation (ATC) from 10°C to 30°C. Comes with case, calibration screwdriver, plastic pipette calibration solution, and user guide.General SpecificationsSalinity0 to 100ppt (10 to 30°C ATC)Salinity Basic Accuracy±0.1%Salinity Max Resolution1ppt