1、3-in-1 Function- It is designed to test TDS(Total Dissolved Solids) and electrical conductivity of water for the purpose of purity. Temperature of water could also be examined. 2、Widely use in drinking water, laboratory, aquarium and water filtration. 3、Features a hold function that saves measurements for convenient reading and recording. 4、The meter uses low-power backlight technology to easily test water at night and in dark places. 5、Made from premium material, reliable and available for long lifespan. Features: 3-in-1 Function- It is designed to test TDS(Total Dissolved Solids) and electrical conductivity of water for the purpose of purity. Temperature of water could also be examined. Widely use in drinking water, laboratory, aquarium and water filtration. Features a hold function that saves measurements for convenient reading and recording. The meter uses low-power backlight technology to easily test water at night and in dark places. Made from premium material, reliable and available for long lifespan. Specification: Condition: 100% Brand new Casing material: ABS Size: approx. 162*30*15mm/ 6.38* 1.18* 0.59in Color: White+Black Measuring range(conductivity): 0-9999us/cm Measuring range(temperature): 0.1℃-50℃（ 32.0℉- 122.0℉） Measuring range(TDS): 0-9999ppm Resolution for TDS: 1ppm Resolution for EC:1us/cm Resolution for temperature:  0.1℃（ 32.0℉） Automatic temperature compensation: 0℃-50℃ Working temperature: 0℃-50℃ Accuracy(TDS/EC): ±2% Power supply: 1*3V CR2032 button battery(not included) How to use: 1. Remove the protective case and press ON/OFF button. 2. Immerse the TDS meter into the water whose height is less than 4cm. 3. Stirring the water tester and waiting the display stabilizes. If you want to manually lock, press the HOLD button. Press the MODE button to select the test function, and select: ppm, conductivity us/cm value, Celsius temperature °C, Fahrenheit temperature °F Package List: 1* Digital Water Tester 1* User Manual   Notice: Please allow slight error due to manual measurement and make sure you do not mind before ordering. Please understand that colors may exist chromatic aberration as the different placement of pictures.