This is a capacitative soil moisture sensor. You can connect it to an analog pin of your Arduino or other microcontroller to get a reading of the soil mositure and use it to measure and monitor watering levels. Great for your intelligent automated garden system....

Being capacitative the unit will not corrode when in contact with moisture for long periods (as resistive sensors will). It has an on-board voltage regulator, so it can be used with 3.3V or 5V power supplies.

It comes with a 3-wire connector lead. The analog output voltage will be proportional to the mositure content so you can track when your plants might need watering.

Specifications are:

• Operating Voltage:  3.3 - 5.5V DC
• Output Voltage:      0 - 3.0V DC

I have written a basic Arduino sketch to read the sensor and give a moisture content percentage. That should get you up and running!