PortaPow 3-20V Dual USB Power Monitor with SmartCharge Technology Plugs into any USB socket, and allows you to connect one or two USB cables into it. It displays on screen the voltage, current and the total amount of current received by your gadgets. USB1: Incorporates PortaPow's SmartCharge adaptor as sold separately. This blocks data transfer allowing you to charge from any USB socket without risk of data hacking / viruses, and detects your device's charging spec to allow upto 2-4x faster charging than is normally possible from computer USB sockets. USB2: A normal USB 2.0 socket, allows data transfer and charging. 0-4000mA (4.0A), 3-20V Range, Resolution of 0.01A, 0.01V. Compatible with Qualcomm Quick Charge 1, 2, 3 Backlit LCD screen with 9 memory positions for storing mAh values and warning buzzer for low/high voltages.