Very good product. A definite recommendation!

I'll try to make a brief description / review.

All parts of the stand are working very stable and good. For installation you only need a Phillips screwdriver with clamp mounting. All bolts and parts are individually wrapped. The good guide is in the form of a double-sided A3 page.

For I have chosen mounting a hole with a diameter of 8-51 mm is needed. I drilled a hole with 8.5 mm in the desk. The counter plate to the stator is approximately 5x8 cm (50x80 mm). Openings for cable entries can therefore be used under certain circumstances.
With the mounting hole of the monitor stand is rock solid and the monitors can be moved over the rear edge of the table, which is not the case with the clamp assembly.

Before you (optionally with M4x10 mm Phillips in silver or M4x10 mm screws in black) connects the monitors with the bracket, you can lock the bracket with a small screw to 0 °. So can no longer switch between landscape and portrait modes.

The mere assembly of ERGOTRON without re-lay cables took about 30 minutes.

Approximately 1,2-1,3m conduction through the arms to the holder of the post should plan around.
Under the upper arm, the cables are fixed with two cable ties. In the lower arm, the cables run in a kind of conduit is completely removable.

Advantages: monitors can be placed in any location. Height / angle / distance. Place among the monitors free / available. Installation is very simple.

Disadvantages: Expensive. Space behind the desk. If the monitors are about 10 cm away from the base and the arms need only 12 cm and even 8 cm behind the desk. The base is 10 cm (center mandrel) mounted from the edge.

Conclusion:
Price / performance ratio is good. The holder is high quality and very well made.