Prime Autobots 4 in 1 Dual USB Car Charger, Voltage Digital Panel Meter Volt Voltmeter Monitor for Auto Car Truck, with LED Display (Red) FAST DUAL USB CHARGING PORTS - Combined 3.1 amps; 15W; uses smart technology to ensure each device pulls the right amperage. Charger is powered by the vehicle's cigarette lighter. OVER-CHARGE PROTECTION - auto power off when input/output is greater than safety current, protects against over-heat, over-current and over-charging LED DISPLAY - LED digital luminescence tubes; Display cycles between internal temperature, device's charging current, and the voltage of the vehicle's car battery. SPECIFICATIONS - Input: DC 12V - 24V, Output: DC 5V/3.1A, 15 W, Conversion efficiency 95%, Measuring range: Voltage 5V-25V, Current 0 - 3.1A, Temperature -4 to 176 F Package Includes: 1 x Dual USB Car Charger with LED Display. (Charging Cable NOT included)