eSeasongear SALT-3050 Waterproof Tester, Digital Salinity PPM Temperature Meter for Salt Water Pool and Koi Fish Pond Precalibrated at 3000 ppm salt (NaCl) Built-in ATC sensor for automatic temperature compensation Built-in salt (NaCl) conversion factor for meter calibration Salt Range: 0-5000ppm or 0.0-0.5% Temperature Range: 1-80 C or 33-176 F