The HI98130 is a highly accurate, waterproof combo ph ec tester that can also measure EC/TDS in the high range (0.00 to 20.00 mS/cm EC/ 0.00 to 10.00 ppt TDS) and temperature. This floating, waterproof combination tester has an easy to read, LCD and an automatic shut-off. In addition, pH and EC/TDS readings are automatically temperature compensated (ATC) to prevent temperature-related variations in your measurements.