Features: 1.LCD USB current and voltage tester with alarm 2.Input Voltage: 4 ? 20V 3.Input Current: 0 ? 4.0A 4.Voltage measurement error : when 4- 20V ,1% 5.Current measurement error : when 0~4000ma ,1% 6.Maximum Capacity Value : 99999 mAh 7.Maximum Save Data Group: 9 This power monitor plugs directly into any USB socket and allows you to connect any USB cable into it for charging or data transfer. It displays on screen the voltage, current and the total amount of current which has been output. It is also allows you to compare the power of different USB sockets, see how much power each of your devices needs, and study the quicks of USB charging. This is especially useful for solar panels with USB outputs, since it will then allow you to position the panel to maximize the energy it outputs, see what factors affect the panel's performance, and also to see when the output is too low to be worth using the solar panel. USB1: Incorporates 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 whether your device uses the Apple, Samsung or Universal Charging spec. In some cases (eg when charging from a PC or a charger built to the wrong spec) it can boost charging speed by upto 4x. In other cases your device may already be charging at full speed. USB2: A normal USB 2.0 socket, allows data transfer and charging. 0-4000mA (4.0A), 4-20V Range, Accurate to 0.01A, 0.01V. Uses 13mA for an accurate readout. Fully compatible with Qualcomm Quick Charge 1.0, 2.0, and also compatible with 3.0 upto 20V 9 different memory positions to store mAh values. Uses a backlit LCD display which can be seen either in complete darkness or bright sunny conditions. Built in extension cable means you can turn the screen to face you. 1 Year Guarantee and Support From UP - 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. Listing and template services provided by inkFrog