Universal design: suitable for any car, SUV, truck. The wireless design does not damage the original car line, just stick it at the door.<br><br>How the warning works: When the door is opened, the red light flashes to warn pedestrians or vehicles behind to avoid accidents or collisions.<br><br>3 modes of flashing ----- 0-7 seconds: All LEDs flash quickly. 7-60 seconds: Each LED flashes in turn. 60-110 seconds: Each LED flashes in a slow vortex. It will automatically shut down after 110 seconds.<br><br>Waterproof design: It can still work after soaking in water for 30 minutes. High-tech component sensing: through IR chip program control, increase sensitivity and maintain product stability.<br><br>Long battery life: This product uses CR2032 button battery (including battery). After testing, it can be used for 1-1.5 years under normal use. The screw cap design can easily replace the battery.<br> Universal design: suitable for any car, SUV, truck. The wireless design does not damage the original car line, just stick it at the door. How the warning works: When the door is opened, the red light flashes to warn pedestrians or vehicles behind to avoid accidents or collisions. 3 modes of flashing ----- 0-7 seconds: All LEDs flash quickly. 7-60 seconds: Each LED flashes in turn. 60-110 seconds: Each LED flashes in a slow vortex. It will automatically shut down after 110 seconds. Waterproof design: It can still work after soaking in water for 30 minutes. High-tech component sensing: through IR chip program control, increase sensitivity and maintain product stability. Long battery life: This product uses CR2032 button battery (including battery). After testing, it can be used for 1-1.5 years under normal use. The screw cap design can easily replace the battery.