It is a Voltmeter Tester/USB Adapter, Measuring Voltage range: DC 8~40V, USB Output Voltage: DC 5.0~5.1V, USB Output Current: 0~2.1A, Function 1: Battery voltage monitoring,for 12V cars, SUV, 24V trucks, buses., Function 2: USB charger, for the charger of 0~2.1A cell phones, digital cameras, tablet computers and etc, Applicable Type: Support Android, suitable for IPhone / Ipad / Ipod.