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; Distribution bit sensitivity adjustment, relay threshold set by adjusting potentiometer, when the dark this threshold, the module relay is energized, bright this threshold, the relay release; using the photoresistor induction light intensity comes with the relay, direct control load has four fixed bolt hole for easy installation, Manufacturer: Akfldms