Solu DC 12V Light Sensor Switch Photosensitive Resistance Relay Module with Cable// DC 12V Stable Car LED Headlight Automatic Light Control Circuit Module//DC 12V Photoelectric Switch Sensor Relay Module 50mmx25mm with 2 Cable About us, Professional factory of circuit boards for Arduino, welcome to our store for more choices with best price. What we pursue is your satisfication of our service, not just for our goods.For any reason you are unsatisfied with our product at any time, simply contact support for exchange or refund. we will reply you about any question you ask within 24 hours Usually, you will get it actually in 9~19 days, If you are in the USA and the item is NOT Fulfilled by Amazon. the item will be sent to you by USPS with shipping information from China. The estimated delivery time offered by Amazon is not the real time. Your patience is highly appreciated. Hope you will receive your item soon and enjoy using it. Light detection, brightness detection, test and adjust brightness threshold via potentiometer, comes with relays, can do all kinds of brightness detection switch. Can control various street lights. They can automatically be opened at night while automaticlly shuts off in the daylight and control the car gadget and automatic equipment.Adopts photosensitive resistance to sense the strength of light, together use with relay, can directly control the load Euipped with potentiometer to adjust the sensitivity. Set and start the relay threshold value by adjusting the potentiometer. When the strength of light is lower than this threshold value, relay module will attract to close while it is higher than the threshold, the relay module will break off