Guide to use this sensor with Arduino can be found here.This is a simple sensor that can be used to detect soil moisture. The module is able to detect when the soil is too dry or wet. Great for use with automatic plant watering systemsSensitivity is adjustable via the blue digital potentiometer Operating voltage 3.3V-5V The module has dual output mode: digital output or analog output giving more accuracy Has pre-drilled hole for easy installation Small board PCB size: 3cm * 1.6cm Power indicator (red) and digital switching output indicator (green) Uses the LM393 comparator chip