4 In 1 Multifunctional: USB charger socket power outlet combines a 12V USB outlet, LED voltmeter, 12V cigarette lighter outlet, and LED rocker switch for versatile use Dual USB Charger: Dual USB ports deliver a total of 4.2A, auto-detecting devices to charge 2 simultaneously at optimal speed Durable LED Rocker Switch: 12v usb socket panel designed for easy use and durability (up to 10,000 cycles) with an added cigarette lighter socket for extra convenience Wiring & Installation Tips: Ensure precise wiring with clear LED backlight connections, noting the brass pin's negative connection. No instruction manual included Wide Compatibility: Auto-detects and charges devices at optimal speed, suitable for cars, boats, RVs, trucks, and more, supporting various vehicle appliances