Product DescriptionDUAL USB CAR CHARGER :Powered by your cars DC outlet(cigarette lighter port).Total 3.1 A; allows charging of two devices at once. With 2 usb ports, you can conveniently charge 2 devices at same time.Compatible with iphone,Samsung,HTC,etc (1A), ipad,Tablets,etc (2.1A).SMART OVER-CHARGE PROTECTION: Intelligent circuit design protects against short circuiting, overheat, overcurrent, and over charge.Charges mobile phone quickly and efficiently.And protect the safety of charging device.BATTERY VOLTAGE METER:Display the voltage of vehicle's battery when no charging.Let you always monitoring the health of battery and peace of mind when drive.A flashing LED display indicates a potential vehicle voltage problem.COMPACT DESIGN FOR MORE PORTABILITY :Fits in the palm of your hand. The slim aluminum profile minimizes any obstruction while charging.TECH SPECS : Input: 12V-24V. Output: 3.1A; Size: 2.3" x 1.4" x 1.4".