This is use smart technology to ensure each device pulls the right amperage. Digital LED displays device's charging current and the voltage of the vehicle's car battery. High-quality and safe, with protections against overheating, over current, over voltage and overcharging. Charging will stop automatically when battery is full. Compatible with Most Android/Windows Smart Cell Phones, Tablets, and Other USB-charged Devices. Certified by RoHS, CE & FCC, high-quality fire proof material.