HiLetgo 5pcs LM393 Soil Moisture Sensor Automatic Watering System for Arduino This is a simple moisture sensor can be used to detect soil moisture, when the soil water shortage, the module outputs a high level, whereas the output low. Use this sensor to make an automatic watering device that will keep your garden of plants unmanaged. Module dual output mode, digital output is simple, more accurate analog output. Sensitivity adjustable (Figure blue digital potentiometer adjustment) Comparator using LM393 chip, stable job