USB 2.0 Digital Multi-Meter Current and Voltage Monitor/Power Meter Tester, Ammeter Voltmeter Capacitance and Watt Meter, 7 Modes Multi Tester, Dual USB Ports

Much better than an LCD one I already have. Large display, readable in daylight. Very handy for monitoring the output of the USB power convertor (by Sinewave Cycles - highly recommended) attached to the dynamo hub on my bicycle.