JINXIU 4 IN 1 DESIGN: This multifunctional panel designed with 12v USB outlet + LED digital display voltmeter+ 12v cigarette lighter outlet + LED rocker toggle switch. Convenient for installation and operation. Also detachable to replace other charger sockets or anything else that fits. DUAL USB CHARGER SOCKET: This waterproof 12v USB outlet charger socket is built-in dual USB charging ports with a cap, and 2 ports output: 5V/2.1A2.1A (total 4.2A), which will auto-detect your devices and simultaneously charging 2 devices at optimal speed REAL-TIME LED VOLTMETER: With a large digital voltmeter display that shows 5-48V voltage, you can monitor the condition of the battery on your car or boat if the voltage is under normal status. OVERCHARGE PROTECTION: Over-heated, over-current, over-charging protection, This dual USB charger power socket is also smart to identify the most appropriate current for your device.