This is a cleverly designed ball head for mounting a camera to a metal surface. The base is a rubberized magnet that has a good amount of force and doesn't feel it would come off easily, and it is also wide which helps prevent movement. The ball head tightens up well and doesn't have any play. The top has a standard 1/4-20 mounting screw that is found on most cameras, and it comes with a mount for GoPro type cameras if you should choose to use it. The photos I've included are intended to show that the base has the ability to slide out and become slightly longer for bigger items. It also flips up and has a spring-loaded arm to hold phones. It will hold a very large phone but it is not wide enough to hold an iPad mini or anything of that size. There is also an additional threaded hole on the base to add additional accessories if you want.

What I like:
-Very clever design, allows standard 1/4-20 mount cameras, GoPros, and phones all in one
-Well machined, tight ball head
-Strong, wide magnet, does not feel like it would come off easily

So-So:
-If using it in a fixed location, it will hold even medium or larger cameras pretty well, but if using it on the outside of a moving vehicle, I would only use smaller cameras, action cameras, or a phone

Bad:
-Nothing really. It does what it is designed to do very well and seems like it was built to last forever.