American Marine PINPOINT Salinity Monitor PINPOINT Salinity Monitor will accurately and immediately measure the amount of salt in any marine or freshwater system. The reading is fully temperature compensated and the conversion chart will precisely show the corresponding density (specific gravity) or % salt (refractometer) values. Every saltwater aquarist should own this monitor . the accuracy is superb! This monitor is especially useful to determine the low level of salt required for Koi, whether in an aquarium or outdoor pond. Comes complete with meter, probe and calibration fluid.