The Lamotte Company 1749 Salt/TDS/Temperature Pocket Tester is an auto-ranging TDS tracer meter that offers 3 ranges to measure pure water to salinity solutions using the same conductivity cell. The Salt PockeTester measures the Sodium Chloride level in salt water pools with a range from 0 to 9,999 ppm. Total dissolved solids (TDS) is a measure of the dissolved combined content of all inorganic and organic substances present in a liquid in molecular, ionized or micro-granular (colloidal sol) suspended form. The tester's probe is dipped into a sample of pool water and the results are ready instantly. It features a simultaneous display of conductivity or TDS and temperature. TDS is measured from 0 to 9,999 ppm and Temperature from 32.0 degrees to 149 degrees Fahrenheit. A memory feature saves up to 25 test results, it can also store and recall 15 readings, as well as the capability to data hold plus auto shut-off and low battery indicator features with automatic temperature compensation. A self-calibration on power-up is also done and it comes complete with meter and conductivity cell, protective sensor cap, and neck strap and completely packaged in a rugged carrying case with a special calibration standard.