using the photoresistor induction light intensity comes with the relay, direct control load Distribution bit sensitivity adjustment, start relay threshold set by adjusting potentiometer, when the dark this threshold, the module relay is energized, bright this threshold, the relay release; 12 V power input is designed for relay board regulator transistor to provide sensor Used to make the product more stable and reliable; onboard optocoupler isolation drive relay, the effective protection of the chip to make the product more reliable work; has four fixed bolt hole for easy installation Material: metal Color: blue With lines,Line color is random Module using the instructions: 1, photoresistors module is most sensitive to ambient light, generally used to detect the brightness of the ambient light. 2, the module when the ambient light is darker than the threshold value is set, the relay is energized, the common terminal and the normally start is turned on, when external ambient light is brighter than the set threshold value, the relay is switched off, the common terminal and the normally closed end connected; 3, the public side, normally open, normally closed three ports, the equivalent of a dual-control switch, relay coil power, public end and often the beginning of conduction, radio, public end normally closed terminal conduction; Supply voltage: 12VDC Current: Greater than 100mA Load: 250V 10A AC or 30V 10A DC (the current is less than this range can be used) Size: 5.3cm x 3cm Quantity:4Pc Package includes: 4Pc xDC 12V Photoresistor Module Relay Light Detection Sensor Light Control Switch Note: Random color, don't accept the specified color. Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.