Review on GutReise Universal 12V Car Charger + 5V DC Power Cable (Max 10A): Perfect for DVD Players, Dash Cameras, GPS, Bluetooth Speakers, Shaver Fans - Includes 11 Connectors by Chris Rigsby

I checked the output voltage and found it to be around 13.1V; the tip is positive and the ring is negative. This set is very useful, at least for me. More and more of my 12v devices come with different sized plugs and I'm getting tired of keeping track of all the different chargers. You can also use the USB cable with any standard 5V power source (phone charger, external battery, etc.) and get 5V into any weird device you use that has a 5V plug. Just do not use the 12V car adapter with 5V devices and vice versa. These are two different charging solutions in the box and they use the same set of adapters. The kit also includes Micro-USB and USB-C adapters, and strangely, there's even a Mini-USB adapter. I've never seen a device that uses this for power, but if you find it you're protected. The only thing not covered is Lightning. So I see it as insurance. If I lose my charger or find myself disconnected from it, I have this kit that can charge almost anything.