Extech RF20  

Extech RF20: Portable Salinity Refractometer (0 to 100ppt) with ATC

Measures the concentration of dissolved salt in fluids

Measures the concentration of dissolved salt in fluids. Compact size, easy to operate. Automatic Temperature Compensation (ATC) from 10 to 30°C. Comes with case, calibration screwdriver, plastic pipette calibration solution, and user guide.