Except for the desk mounting hardware, the mount comes fully assembled, as depicted in the promotional image below.
The USB cables are pre-installed, and I was actually pleased to see it does not have a hub, just two USB extension cables with very long leads. This way, you can run the cables back to your system, even if it isn't all that close to your monitor, and even if you don't have USB 3.0 ports. You can use these for USB 3.0 or USB 2.0, and since there is no hub you don't have to worry about extra power supplies or possible transfer speed losses.
The next two images show the more on the USB cables and how they attach to the mount. It really is simple, with just a set of female connectors affixed to the mount so they are available on the mount's front bezel.
The images below take a look at some of the various joints on the RMS-16003. You have plenty of degrees of freedom for adjusting your monitor's height, spacing, tilt, swivel, rotation, etc. The joint in the below right image shows an allen screw tension adjuster which you will have to tighten in order to hold your monitors up. It is set to be very loose so the mount can be folded up in the box, and you actually have to crank this in the opposite direction of the typical tightening convention... as labeled, counter-clockwise is tighter, no looser like a typical screw.