4 in 1 Design - This multi-function panel is designed with 12v USB socket + LED digital display voltmeter + 12v cigarette lighter socket + LED rocker switch. Convenient to install and use. Also detachable to replace other charger sockets or anything that fits. Waterproof Dual USB Charging Socket - This 12v USB charging socket has built-in dual USB charging ports, dual port output: 5V/2.1A and 2.1A (total 4.2A), will automatically detect your devices and charge 2 devices simultaneously at optimal speed! Real-time LED Voltmeter With a large digital voltmeter display showing 5-48V voltage, you can monitor your car or boat battery status whether the voltage is under normal status. LED On/Off Rocker Switch - Designed with rocker style, easy to use. Long lifespan up to 10000 cycles. An extra cigarette lighter socket is portable for other devices in your vehicle. Overload Protection - Overheated, overcurrent, overload protection; This dual USB charger socket is also intelligent to identify