Review on YONHAN Quick Charge 3.0 Dual USB Charger Socket - Waterproof Power Outlet for 12V/24V Car Boat Marine ATV Bus Truck - LED Voltmeter & Wire Fuse Included - Deep Blue by Joshua Castillo

USB charging ports are as advertised, but if your charging cables aren't compatible with this technology, you won't see fast charging results. You can, it's just that Spending twice what this device costs to get the right cables to use the fast charge feature. The voltmeter is sufficiently accurate for a layman, but deviates fairly constantly by 0.2-0.3 volts. In most cases this doesn't matter much, but be aware that if you expect high accuracy, you will be disappointed. UPDATE: AFTER 3 MONTHS, A CHARGING PORT IS NOT WORKING AND THE VOLTAGE METER BLINKS AND GOES ON AND OFF, BUT EVEN DURING OPERATION IT FLASHES SO MUCH THAT THE NUMBERS CANNOT BE RECOGNIZED. Well, I don't have to say the impossible - yesterday the numbers were clearly visible and read 15.9 volts. I'm not a vehicle electrician, but I think that's at least a few volts lower. DO YOU REALLY WANT TO CHECK THE DIAMETER OF THE HOLE IN YOUR FINISHED PANELS FOR A PRODUCT THAT CAN BE LOST AFTER 3 MONTHS?