Measuring range: conductivity: 0-9990 us/cm, TDS: 0-9999 ppm, Celsius: 0.1-80.0 , Fahrenheit: 32.0-176.0 , accuracy: 2%, size: 154 30 14 mm, net weight: 55g3 in 1 design: water quality tester consists of TDS meter, EC meter and temperature meter. You can use the mini water quality pen to test water used for drinking, hydroponics or filling your aquarium.Auto-off and hold function: the TDS tester will automatically turn off after 10 minutes of non-use to save the batteries. Has a hold function that stores measurements for convenient reading and recording.Multi-mode conversion: you can switch between TDS and conductivity by clicking the SHIFT button. Press and hold the SHIFT button twice to switch between Celsius and Fahrenheit.