HOW THE WARNING WORK: When the door opened, the RED light flashing, White light stays bright,warning the rear pedestrian or vehicle, to avoid accident or collision., Do not destroy the original car lines, just paste it in the door and connect the positive and negative power supply to power on, WATERPROOF DESIGN: Soaked in water for 30 minutes, still can work. High-tech component sensing: through the IR chip program control, increase the sensitivity, to maintain the stability of the product.