DC12V Soil Moisture Sensor Relay Control Module Automatic Watering Switch Features: This module can control humidity of soil in a wide range and set control threshold by adjusting potentiometer. When humidity is lower than the set value, relay is energized;  when humidity is higher than the set value, relay is dis-energized. soil moisture sensor has nickel plating surface, widened induction area, can improve conductive performance and prevent rust problem when contact with the soil to prolong service life. It has time delay function, delay 3-5 seconds, when humidity is detected in the threshold state, the relay will not flicker. Adjusting soil moisture control threshold by potentiometer (clockwise to increase, counterclockwise to reduce), it can control soil humidity and automatically watering vegetable garden, flower garden or pot.   Because this module has time delay function, when  adjusting humidity, you need to wait for 5 to 8 seconds to check the change of relay, and the green LED lights will change, until it is adjusted as required. Specifications: Power Supply Voltage: 12VDC　　 Max. Load Power: 1500W Module Size: 1.7*5*2.5cm/0.67*1.97*0.98in Package Includes: 1 x Module 1 x Sensor 2 x Cables