Semlos LCD Display Digital Multifunctional TDS Meter, Measure Tds, Ec and Temp, Water Quality Tester for Household Drinking Water and More Professional quality combination TDS, EC and Temperature Meter. The TDS & EC Meter is a professional level meter at an unbeatable price. Lock function - makes it easy to read and record, press HOLD button then remove from test solution. Automatic Temperature Compensation (ATC) using three temperature coefficients . 5 minute Auto Shut Off feature, so battery won't run down.