Wall mounting: the brackets are easy with no screws to mount on the wall. The angle of the boxes can be easily removed for and after installation.
Mounting boxes: the boxes are each set at an angle and is locked with a screw supplied from behind. There is a lack of fit. Even under great force application, the hole and the socket is not bringing in the box cover, the screws can only inclined / tilted and not fully be turned into the socket of the boxes. The canted mounting stands but under tension and sits without wobbling.
Conclusion: the boxes are securely mounted. You can swing in both directions by 45 °, tilt downwards and remove it if necessary including mounting brackets easy. Functionally defnitiv good!
Those who value material and fit, should firmly make its decision on price. If I had not made the hasty holes, I would have given the article due to the combination of material, especially the lack of fit and not least the current price of 70 EUR back.