When you need absolutely accurate salinity conditions in your aquarium, you're going to need an H2 Ocean Seawater Refractometer. Unlike other refractometers on the market, the H2 Show Refractometer measures "true" seawater salinity levels, instead of just saltwater. This means that it measures usually unaccounted for elements such as calcium and magnesium as well as sodium chloride, giving highly accurate, precise results.
True calibration of your seawater levels creates the ideal environment for fish to thrive. Other features include a finer scale running from 20-40ppt salinity (SG 1.015 - 1.030), 20/20 calibration at room temperature for more consistency and accuracy in everyday use, and full ATC (auto temperature compensation) ranging from 5 to 30 degrees C.
Not pleased with the product. It was heavier and felt like it was better quality than other refractometers, but not the case. The eye piece broke from the adjustments to focus it and what was needed to turn it so it would fit back into its case.I was able to repair that. I bought seawater test fluid to calibrate it, and out of curiosity I tested it with this and the recommended way using RO water. Got two different calibrations. Called the company and they did answer, but said the test fluid I had must be for a brine and to trust the RO water. The fluid I bought was specific to "seawater" not brine or brix ( I researched and made sure). Finally the inside scale broke and is rattling around inside the unit, completely unusable. I purchased a much cheaper model and am much happier. I appreciate quality in the hobby and am not afraid to pay for it, but this fell far short of the mark.