Universal Design: Suitable for all cars, SUVs, trucks. Wireless design, won't destroy the original lines of the car, just stick it to the door. How the warning works: When the door is opened, the red light flashes, warns rear pedestrians or the vehicle to avoid any accident or collision. 3 flashing modes: 0 to 7 seconds: All LEDs flash quickly. 7 to 60 seconds: each LED flashes sequentially. 60 to 110 seconds: each LED flashes slowly. Auto power off after 110 seconds. Waterproof design: Soak in water for 30 minutes, still can work. High-tech component detection: Through the IR chip program control, increase the sensitivity, to maintain product stability. Long battery life: The product uses a CR2032 button battery ( battery is included), through testing, under normal working condition, you can use 1-1.5 years, with screw cap, can easily replace the battery LED size: diameter 2.9cm x 0.9cm thickness. Magnet size: 2cm diameter x 0.4mm thickness. Color: as shown (red light) Quantity: 4 pieces