Description: This four-hole panel includes 2 USB charger socket (Output: DC 5V / 2.1A) + Voltage Meter + 12V power outlet (Output: DC 12V) + ON-OFF Toggle Switch, they are interchangeable. You also can replace any port with additional USB outlets, or anything else that fits. Widely used for 6-24V car, truck, Motorcycle, RV, ATV, boat, Camper Vehicles, etc. Easy to install and convenient to use. The USB socket Fits for charging any 6-24V devices and charges fast for HTC, , Blackberry, MP3 Players, Digital Cameras, PDAs, and Mobile Phones. display the current detected by the intelligent circuitry while charging. Intelligent circuit design protects against excessive current, overheating, and overcharging. Ensure the charging safety. The voltmeter shows 6-24V voltage when driving which can remind you whether the voltage is at a normal level, ensure driving safety. Specification: Color: Black Material: ABS +Aluminum plate Voltmeter socket dimension: Approx. 2.8 * 1.6cm (Screw Diameter * Height) USB socket dimension: Approx. 2.9 * 4cm (Screw Diameter * Height) Power socket dimension: Approx. 2.9 * 4cm (Screw Diameter * Height) ON-OFF Toggle Switch: Approx. 2.9 * 1.8cm (Screw Diameter * Height) Four hole panel dimension: Approx. 10.5 * 8.7 * 0.5cm (L * W * H) Package Includes: Package Contents: 1 Piece Four Hole Panel Base 1 Piece Double USB with BLUE voltage display Car charger 2 Pieces Power Outlet 1 Piece ON-OFF Toggle Switch 2 Pieces Heat shrinkable tube 4 Pieces screws : Regarding the each usb port 2.1A, it meant the maxi ampere of each usb port is 2.1A, if your device has no 2.1A itself, you use the ammeter could not test 2.1A. and you can use the device has 2.1 itself, for example: you can use ipad to test it, it can prove each usb port is 2.1A.