Product Description: Versatile: Combines a TDS meter, an EC meter, and a thermometer in one ergonomic pen. Can test ppm, conductivity, Celsius, and Fahrenheit. Reasonable Design: Intelligent backlight design, automatic lock function, large screen display, automatic temperature compensation, automatic shutdown after 2 minutes to save battery power. Auto lock and hold function: After the reading is stable, it will automatically lock after a few seconds, which is convenient for reading and recording; Before automatic reading, press HOLD to manually lock the reading. ACCURATE AND EASY TO CARRY: Sensitive exposed sensor element for accurate measurements in 5 seconds, pocket-sized, durable, long battery life. Wide range of applications: Testing tap water, filtered water, distilled water, bottled water, well water and chilled water. Widely used in all water quality testing, water purification applications, aquaculture, hydroponics, pools and spas, colloidal silver, water treatment, and more.