KONNWEI USB Digital Multimeter DC 3-8V 3A Volt Amp Meter, Voltage and Current Tester Charging Monitor with Red Light LED Display Operating voltage range: 4.5 - 5.7V DC; Operating current range: 0 - 3A Voltage accuracy: + / -0.5%, resolution: 0.01V; Current accuracy: + / -1%, resolution: 0.01A Sense resistor: 10m; Static power consumption: 20mA; Dimensions: 43x25x11mm Full charge off automatically, to avoid overcharging; Overvoltage/Overcurrent protection A great tool for testing phones, tablets, USB ports, power supply, charger outputs, and current demands of USB devices