Wiring & Installation Notes: Specify the switch's backlight LED connections and stress precise drilling during installation. (Note the brass pin's negative connection for the switch's backlight LED, ensuring proper wiring (no instruction manual provided). Multifunctional 4-in-1 Design: Features a versatile combination including a 12V RV USB outlet, LED voltmeter, 12V cigarette lighter outlet, and an LED rocker switch. Dual 12V USB Charger: Equipped with two USB ports delivering a total of 4.2A simultaneously, will auto-detect your devices and simultaneously charge 2 devices at optimal speed! User-Friendly LED Rocker Switch: Engineered for easy operation and durability (up to 10,000 cycles). Featuring an additional cigarette lighter socket for added convenience. Optimized Device Compatibility: Automatically detects and charges devices at their optimal speed, offering a portable socket for various vehicle appliances.Suitable for cars, marine vessels, boa